Display device and electronic device

ABSTRACT

A display device that can display an image along a curved surface is provided. In the display device, a first display panel and a second display panel overlap each other with a light-transmitting layer provided therebetween. The light-transmitting layer is positioned on a display surface side of the first display panel, and on a side opposite to the display surface of the second display panel. The light-transmitting layer has an average transmittance of 80% or more with respect to light in the wavelength range of 450 nm to 700 nm and a refractive index higher than that of air. A display region of the first display panel overlaps a region transmitting visible light of the second display panel with the light-transmitting layer provided therebetween. It is preferred that the display region of the first display panel not overlap with a region blocking visible light of the second display panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/121,702, filed Sep. 5, 2018, now allowed, which is a continuation ofU.S. application Ser. No. 14/806,950, filed Jul. 23, 2015, now U.S. Pat.No. 10,159,135, which claims the benefit of foreign priorityapplications filed in Japan as Serial No. 2014-156168 on Jul. 31, 2014,Serial No. 2014-219131 on Oct. 28, 2014, Serial No. 2014-243195 on Dec.1, 2014, and Serial No. 2015-109642 on May 29, 2015, all of which areincorporated by reference.

TECHNICAL FIELD

One embodiment of the present invention relates to a display device, anelectronic device, or a manufacturing method thereof. The presentinvention particularly relates to a display device or an electronicdevice utilizing electroluminescence (hereinafter also referred to asEL) or a manufacturing method thereof.

Note that one embodiment of the present invention is not limited to theabove technical field. Specifically, examples of the technical field ofone embodiment of the present invention disclosed in this specificationinclude a semiconductor device, a display device, a light-emittingdevice, a power storage device, a storage device, an electronic device,a lighting device, an input device (e.g., a touch sensor), aninput-output device (e.g., a touch panel), a driving method thereof, anda manufacturing method thereof.

BACKGROUND ART

In recent years, larger display devices have been required. Examples ofuses for a large display device include a television device for home use(also referred to as a TV or a television receiver), digital signage,and a public information display (PID). A larger display region of adisplay device can provide the increased amount of information at atime. In addition, a larger display region attracts more attention, sothat the effectiveness of the advertisement is expected to be increased,for example.

In addition, for application to mobile devices, larger display deviceshave been required. In recent years, browsability has been considered tobe improved by increasing the amount of information to be displayed atone time with an increase of a display region of the display device.

Light-emitting elements utilizing EL (also referred to as EL elements)have features such as ease of thinning and lightening, high-speedresponse to input signal, and driving with a direct-current low voltagesource; therefore, application of the light-emitting elements to displaydevices has been proposed. For example, Patent Document 1 discloses anexample of a display device including an organic EL element.

Furthermore, Patent Document 2 discloses a flexible active matrixlight-emitting device in which an organic EL element and a transistorserving as a switching element are provided over a film substrate.

PATENT DOCUMENT [Patent Document 1] Japanese Published PatentApplication No. 2002-324673 [Patent Document 2] Japanese PublishedPatent Application No. 2003-174153 DISCLOSURE OF INVENTION

An object of one embodiment of the present invention is to increase thesize of a display device. Another object of one embodiment of thepresent invention is to suppress display unevenness or luminanceunevenness of a display device. Another object of one embodiment of thepresent invention is to reduce the thickness or weight of a displaydevice. Another object of one embodiment of the present invention is toprovide a display device that can display an image along a curvedsurface. Another object of one embodiment of the present invention is toprovide a highly browsable display device.

Another object of one embodiment of the present invention is to providea novel display device, a novel electronic device, or the like.

Note that the descriptions of these objects do not disturb the existenceof other objects. In one embodiment of the present invention, there isno need to achieve all the objects. Other objects can be derived fromthe description of the specification, the drawings, and the claims.

One embodiment of the present invention is a display device at leastpart of which is flexible. The display device includes a first displaypanel, a second display panel, and a light-transmitting layer. The firstdisplay panel includes a first region. The first region has a functionof performing display. The second display panel includes a second regionand a third region. The second region has a function of performingdisplay. The third region is adjacent to the second region and has afunction of transmitting visible light. In the light-transmitting layer,a transmittance with respect to light in a wavelength range of 450 nm to700 nm is 80% or more on the average. A refractive index of thelight-transmitting layer is higher than that of air. Thelight-transmitting layer is between the first display panel and thesecond display panel. The light-transmitting layer is positioned on botha display surface side of the first display panel and a side opposite toa display surface side of the second display panel. The third regionincludes a region that overlaps the first region with thelight-transmitting layer provided therebetween.

Note that in one embodiment of the present invention, in at least partof the light-transmitting layer, a transmittance with respect to lightin a wavelength range of 450 nm to 700 nm may be 80% or more, preferably90% or more. Similarly, a refractive index of at least part of thelight-transmitting layer may be higher than that of air and preferablyhigher than or equal to 1.3 and lower than or equal to 1.8.

In each of the above structures, the first region and the second regionmay each include a light-emitting element.

In each of the above structures, the third region may include a bondinglayer. Here, the bonding layer may be positioned along part of an outeredge of the second region.

In each of the above structures, the second display panel may include afourth region. The fourth region is adjacent to the second region andhas a function of blocking visible light. It is preferred that thefourth region do not include a region overlapping with the first region.The fourth region may include a wiring. Here, the wiring may beelectrically connected to a light-emitting element included in thesecond region. The wiring may be positioned along another part of theouter edge of the second region.

In each of the above structures, it is preferred that thelight-transmitting layer be detachably in contact with at least one ofthe first display panel and the second display panel.

In each of the above structures, the light-transmitting layer preferablyincludes an inert material.

In each of the above structures, the light-transmitting layer preferablyincludes a non-volatile material.

In each of the above structures, the light-transmitting layer mayinclude a material with a viscosity of greater than or equal to 1 mPa·sand less than or equal to 1000 Pa·s. The viscosity of the material ispreferably 1 Pa·s or more, more preferably 10 Pa·s or more, still morepreferably 100 Pa·s or more.

In each of the above structures, a flexible printed circuit (FPC) may beincluded. Here, the FPC may be electrically connected with the firstdisplay panel. The FPC preferably includes a region overlapping with thesecond region.

One embodiment of the present invention also includes an electronicdevice or a lighting device including a display device with any of theabove structures. For example, one embodiment of the present inventionis an electronic device including the display device with any of theabove structures, and an antenna, a battery, a housing, a speaker, amicrophone, an operation switch, or an operation button.

According to one embodiment of the present invention, the display devicecan be increased in size. According to one embodiment of the presentinvention, display unevenness or luminance unevenness of the displaydevice can be suppressed. According to one embodiment of the presentinvention, the display device can be thin or lightweight. According toone embodiment of the present invention, a display device that candisplay an image along a curved surface can be provided. According toone embodiment of the present invention, a highly browsable displaydevice can be provided.

According to one embodiment of the present invention, a novel displaydevice, a novel electronic device, or the like can be provided.

Note that the description of these effects does not disturb theexistence of other effects. One embodiment of the present invention doesnot necessarily achieve all the effects listed above. Other effects canbe derived from the description of the specification, the drawings, andthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1C illustrate examples of a display device.

FIGS. 2A to 2D illustrate examples of a display panel.

FIGS. 3A to 3C illustrate examples of a display device.

FIGS. 4A to 4F illustrate examples of a display device.

FIGS. 5A to 5F illustrate examples of a display device.

FIGS. 6A to 6C illustrate an example of a display panel.

FIGS. 7A to 7C illustrate an example of a display panel.

FIGS. 8A to 8C illustrate examples of a display device.

FIGS. 9A to 9C illustrate examples of a light-emitting panel.

FIGS. 10A to 10C illustrate examples of a light-emitting panel.

FIGS. 11A and 11B illustrate examples of a light-emitting panel.

FIGS. 12A to 12C illustrate an example of a touch panel.

FIGS. 13A and 13B illustrate an example of a touch panel.

FIGS. 14A to 14C illustrate examples of a touch panel.

FIGS. 15A to 15C illustrate examples of a touch panel.

FIG. 16 illustrates an example of a touch panel.

FIG. 17 illustrates an example of a touch panel.

FIGS. 18A to 18F illustrate examples of an electronic device and alighting device.

FIGS. 19A1, 19A2, 19B, 19C, 19D, 19E, 19F, 19G, 19H, and 19I illustrateexamples of an electronic device.

FIG. 20 illustrates an example of a display device.

FIGS. 21A and 21B are photographs of a display device in Example 1, andFIG. 21C illustrates a display device in Example 1.

FIG. 22A illustrates a display panel in Example 1, and FIG. 22Billustrates a stacked layer structure of a region transmitting visiblelight in Example 1.

FIG. 23 shows a measurement result of a transmittance with respect tolight of a region transmitting visible light.

FIG. 24A is a photograph of a display device, and FIG. 24B is aphotograph of a display panel in Example 2.

FIG. 25 shows a light-emitting element in Example 2.

FIG. 26 shows a measurement result of luminance of a display panel inExample 2.

FIG. 27 shows a photograph displayed by a display device in Example 2.

FIG. 28A illustrates a display panel in Example 3, and FIGS. 28B and 28Cillustrate the way to overlap the display panels.

FIGS. 29A to 29C are photographs illustrating a bending test in Example3, and FIGS. 29D and 29E show photographs of images displayed on displaypanels in Example 3.

FIG. 30A illustrates a photograph displayed by a display panel inExample 3, and FIG. 30B illustrates a method for driving a displaydevice in Example 3.

FIG. 31 illustrates a photograph displayed by a display device inExample 3.

FIG. 32 illustrates a photograph displayed by a display device inExample 3.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments will be described in detail with reference to drawings. Notethat the present invention is not limited to the description below, andit is easily understood by those skilled in the art that various changesand modifications can be made without departing from the spirit andscope of the present invention. Accordingly, the present inventionshould not be interpreted as being limited to the content of theembodiments below.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. Further, the same hatching pattern is appliedto portions having similar functions, and the portions are notespecially denoted by reference numerals in some cases.

In addition, the position, size, range, or the like of each structureillustrated in drawings is not accurately represented in some cases foreasy understanding. Therefore, the disclosed invention is notnecessarily limited to the position, the size, the range, or the likedisclosed in the drawings.

Note that the terms “film” and “layer” can be interchanged with eachother depending on the case or circumstances. For example, the term“conductive layer” can be changed into the term “conductive film”. Also,the term “insulating film” can be changed into the term “insulatinglayer”.

Note that in this specification, examples of the case where X and Y areelectrically connected include the case where A and B are directlyconnected without another element interposed therebetween and the casewhere one or more elements that enable electrical connection between Xand Y (e.g., a switch, a transistor, a capacitor, an inductor, aresistor, a diode, a display element, a light-emitting element, or aload) are connected between X and Y. A switch is controlled to be on oroff That is, a switch is conducting or not conducting (is turned on oroff) to determine whether current flows therethrough or not.Alternatively, the switch has a function of selecting and changing acurrent path.

Embodiment 1

In this embodiment, a display device of one embodiment of the presentinvention will be described with reference to FIGS. 1A to 1C, FIGS. 2Ato 2D, FIGS. 3A to 3C, FIGS. 4A to 4F, FIGS. 5A to 5F, FIGS. 6A to 6C,FIGS. 7A to 7C, and FIGS. 8A to 8C.

A plurality of display panels are arranged in one or more directions(e.g., in one column or in matrix), whereby a display device with alarge display region can be manufactured.

In the case where a large display device is manufactured using aplurality of display panels, each of the display panels is not requiredto be large. Therefore, an apparatus for manufacturing the display paneldoes not need to be increased in size, so that space-saving can beachieved. In addition, since an apparatus for manufacturing small andmiddle-size display panel can be used, a novel manufacturing apparatusdoes not need to be used for increasing the size of a display device, sothat manufacturing cost can be reduced. Furthermore, a decrease in yieldcaused by increasing the size of a display panel can be suppressed.

A display device having a plurality of display panels have a largerdisplay region than a display device having one display panel when thedisplay panels have the same size, so that the display device having theplurality of display panels have an effect of displaying moreinformation on one screen, or the like.

However, each of the display panels has a non-display region thatsurrounds a display region. Thus, for example, in the case where outputimages of a plurality of display panels are used to display one image,the image appears divided to a user of the display device.

Although narrowing the non-display regions of display panels (usingdisplay panels with narrower frames) can prevent the images of thedisplay panels from appearing divided, it is difficult to totally removethe non-display region.

In addition, a smaller non-display region leads to a decrease in thedistance between the edge of the display panel and an element in thedisplay panel, so that the element easily deteriorates by impuritiesentering from the outside of the display panel in some cases.

Thus, in the display device of one embodiment of the present invention,a plurality of display panels are arranged to partly overlap oneanother. In two display panels overlapping with each other, at least adisplay panel positioned on the display surface side (upper side)includes a region transmitting visible light that is adjacent to adisplay region. In the display device of one embodiment of the presentinvention, the display region of the display panel positioned on a lowerside and the region transmitting visible light of the display panelpositioned on the upper side overlap with each other. Therefore, anon-display region between the display regions of the two display panelsoverlapping with each other can be reduced or even removed. Accordingly,a large display device in which a seam between display panels is hardlyrecognized by a user can be obtained.

In one embodiment of the present invention, at least part of thenon-display region of the display panel positioned on the upper side isa region transmitting visible light, and can overlap the display regionof the display panel positioned on the lower side. In one embodiment ofthe present invention, at least part of the non-display region of thedisplay panel positioned on the lower side can overlap with a displayregion of the display panel positioned on the upper side or a regionblocking visible light thereof. It is not necessary to reduce the areasof these regions because a reduction in the area of the frame of thedisplay device (a reduction in area except a display region) is notaffected by these regions.

In addition, a larger non-display region leads to an increase in thedistance between the edge of the display panel and an element in thedisplay panel, so that the deterioration of the element due toimpurities entering from the outside of the display panel can besuppressed. For example, in the case where an organic EL element is usedas a display element, as the distance between the edge of the displaypanel and the organic EL element in the display panel increases,impurities such as moisture or oxygen are less likely to enter (or lesslikely to reach) the organic EL element from the outside of the displaypanel. Since a sufficient area of the non-display region can be securedin the display device of one embodiment of the present invention, ahighly reliable large display device can be realized even when a displaypanel including an organic EL element or the like is used.

When air exists between the region transmitting visible light of thedisplay panel positioned on the upper side and the display region of thedisplay panel positioned on the lower side, part of light extracted fromthe display region is reflected at the interface between the displayregion and air and the interface between air and the region transmittingvisible light, which may result in a decrease in luminance of thedisplay. Therefore, the light extraction efficiency of the region inwhich a plurality of display panels overlap with each other isdecreased. In addition, luminance difference occurs between part of thedisplay region of the display panel positioned on the lower side thatoverlaps with the region transmitting visible light of the display panelpositioned on the upper side and part thereof that does not overlap withthe region transmitting visible light of the display panel positioned onthe upper side, so that a seam between the display panels is easilyrecognized by a user in some cases.

In the display device of one embodiment of the present invention, alight-transmitting layer having a refractive index higher than that ofair and transmitting visible light is provided between the displayregion and the region transmitting visible light. Thus, air can beprevented from entering between the display region and the regiontransmitting visible light, so that the reflection at the interface dueto a difference in refractive index can be suppressed. In addition,display unevenness or luminance unevenness of the display device can besuppressed.

Specifically, one embodiment of the present invention is a displaydevice including a first display panel, a second display panel, and alight-transmitting layer. The first display panel includes a firstregion. The first region has a function of displaying an image. Thesecond display panel has a second region and a third region. The secondregion has a function of displaying an image. The third region isadjacent to the second region and has a function of transmitting visiblelight. In the light-transmitting layer, the transmittance of light in awavelength range of 450 nm to 700 nm is 80% or more on the average. Thelight-transmitting layer has a refractive index higher than that of air.The light-transmitting layer is provided between the first display paneland the second display panel. The light-transmitting layer is positionedon both a display surface side of the first display panel and a sideopposite to the display surface side of the second display panel. Thethird region includes a region that overlaps the first region with thelight-transmitting layer provided therebetween.

At least part of the display device may have flexibility. At least partof the display panel may have flexibility. The display device of oneembodiment of the present invention preferably includes a flexibledisplay panel. In that case, a large curved display device or a flexibledisplay device can be provided, and the application is expanded. Here,an organic EL element is suitably used as a display element.

Note that the transmittance with respect to visible light in thelight-transmitting layer is preferably higher because the lightextraction efficiency of the display device can be increased. Forexample, a transmittance with respect to light in the wavelength rangeof 450 nm to 700 nm of the light-transmitting layer may be 80% or more,and preferably 90% or more.

The difference in refractive index between the light-transmitting layerand a layer in contact with the light-transmitting layer is preferablysmaller because the reflection of light can be suppressed. For example,the refractive index of the light-transmitting layer is higher than thatof air, preferably higher than or equal to 1.3 and lower than or equalto 1.8. The difference in the refractive index between thelight-transmitting layer and the layer in contact with thelight-transmitting layer (e.g., a substrate included in the displaypanel) is preferably lower than or equal to 0.30, more preferably lowerthan or equal to 0.20, still more preferably lower than or equal to0.15.

It is preferred that the light-transmitting layer be detachably incontact with at least one of the first display panel and the seconddisplay panel. In the case where each of the display panels included inthe display device is detachable, when malfunction is occurred in one ofdisplay panels, for example, only the defective display panel can beeasily replaced with a new display panel. By using the other displaypanels continuously, the display device can be used longer and at lowercost.

When there is no need to attach and detach the display panels, thedisplay panels are fixed to each other with the light-transmitting layerincluding a material having an adhesive property (adhesive or the like).

Any of an inorganic material and an organic material can be used for thelight-transmitting layer. A liquid substance, a gelatinous substance, ora solid substance can be used for the light-transmitting layer.

For the light-transmitting layer, a liquid substance such as water, asolution, a fluorine-based inactive liquid, a refractive liquid,silicone oil, or the like can be used, for example.

In the case where the display device is inclined to the horizontal plane(a plane perpendicular to a direction in which gravity acts) or in thecase where the display device is placed so as to be perpendicular to thehorizontal plane, the viscosity of a liquid substance is preferably 1mPa·s or more, more preferably 1 Pa·s or more, still more preferably 10Pa·s or more, and yet still preferably 100 Pa·s or more. In the casewhere the display device is placed so as to be parallel to thehorizontal plane or the like, the viscosity of the liquid substance isnot limited thereto.

The light-transmitting layer is preferably inactive because anotherlayer included in the display device can be prevented from beingdamaged, or the like.

A material included in the light-transmitting layer is preferablynonvolatile. Accordingly, entry of air to the interface due tovitalization of a material used for the light-transmitting layer can beprevented.

For the light-transmitting layer, a high molecular material can be used.Examples of such a high molecular material include a resin such as anepoxy resin, an acrylic resin, a silicone resin, a phenol resin, apolyimide resin, an imide resin, a polyvinyl chloride (PVC) resin, apolyvinyl butyral (PVB) resin, and an ethylene vinyl acetate (EVA)resin. Alternatively, a two-component-mixture-type resin may be used. Avariety of curable adhesives such as a reactive curable adhesive, athermosetting adhesive, an anaerobic adhesive, and a photo curableadhesive such as an ultraviolet curable adhesive containing at least oneof these resins may be used. The adhesives are not necessarily cured inthe case where the display panels are not fixed to each other, or thelike.

The light-transmitting layer preferably has high self-attachability toan object. In addition, the light-transmitting layer preferably has highseparability against an object. After the light-transmitting layerattached to the display panel is separated from the display panel, it ispreferred that the light-transmitting layer be able to be attached tothe display panel again.

In addition, it is preferred that the light-transmitting layer have noadhesiveness or low adhesiveness. Thus, attachment of thelight-transmitting layer to an object and separation of thelight-transmitting layer from the object can be repeated withoutdamaging or contaminating the surface of the object.

As the light-transmitting layer, a film having attachability or a filmhaving adhesiveness can be used, for example. In the case where anattachment film having a stacked-layer structure of an attachment layeror an adhesive layer and a base material is used, the attachment layeror the adhesive layer may function as the light-transmitting layer ofthe display device of one embodiment of the present invention, and thebase material may function as a substrate included in the display panel.The attachment film may include an anchor layer between the attachmentlayer or the adhesive layer and the base material. The anchor layer hasa function of enhancing the adhesiveness between the attachment layer orthe adhesive layer and the base material. In addition, the anchor layerhas a function of smoothing the coated surface of the attachment layeror that of the adhesive layer of the base material. In this manner,bubbles can be made hardly generated between the object and thelight-transmitting layer.

For example, a film in which a silicone resin layer and a polyester filmare stacked can be preferably used in the display device of oneembodiment of the present invention. Here, the silicone resin layer hasattachability and functions as the light-transmitting layer. Thepolyester film serves as a substrate included in the display panel. Notethat a substrate included in the display panel may be further providedin addition to the polyester film.

In the case where a film in which an attachment layer, a base material,and an adhesive layer or a bonding layer are stacked is used, theattachment layer serves as the light-transmitting layer of the displaydevice of one embodiment of the present invention; the base materialfunctions as a substrate included in the display panel; and the adhesivelayer or the bonding layer serves as a layer for attaching an elementlayer and the substrate of the display panel.

The thickness of the light-transmitting layer is not particularlylimited. For example, the thickness may be greater than or equal to 1 μmand less than or equal to 50 μm. The thickness of the light-transmittinglayer may be larger than 50 μm; however, the thickness of the displaydevice is preferably set such that the flexibility of the display deviceis not reduced in the case where the flexible display device ismanufactured. For example, the thickness of the light-transmitting layeris preferably greater than or equal to 10 μm and less than or equal to30 μm. In addition, the thickness of the light-transmitting layer may beless than 1 μm.

Hereinafter, specific examples of the display device of one embodimentof the present invention are described with reference to drawings.

Hereinafter, to distinguish the display panels from each other, the samecomponents included in the display panels from each other, or the samecomponents relating to the display panels from each other, letters areadded to reference numerals. Unless otherwise specified, “a” is added toreference numerals for a display panel and components placed on thelowest side (the side opposite to the display surface side), and to oneor more display panels and components placed thereover, “b”, “c”, andthe like are added in alphabetical order from the lower side.Furthermore, unless otherwise specified, in describing a structure inwhich a plurality of display panels is included, letters are not addedwhen a common part of the display panels or the components is described.

The display device of one embodiment of the present invention includes aplurality of display panels in one or more directions.

FIG. 1A is a top view of a display device 10. The display device 10illustrated in FIG. 1A includes three display panels 100 illustrated inFIG. 2B arranged in one direction (a lateral direction).

FIGS. 1B and 1C are perspective views of the display device 10 differentfrom that in FIG. 1A. The display device 10 in FIGS. 1B and 1C includesfour display panels 100 illustrated in FIG. 2C arranged in a matrix oftwo rows and two columns (two display panels in the vertical directionand those in the lateral direction). FIG. 1B is a perspective view ofthe display device 10 on the display surface side. FIG. 1C is aperspective view of the display device 10 on the side opposite to thedisplay surface side.

FIGS. 1A to 1C illustrate examples where each of the display panels iselectrically connected to an FPC.

A display panel which can be used for the display device 10 is describedwith reference to FIGS. 2A to 2D. FIGS. 2A to 2D illustrate examples ofa top view of the display panel 100.

The display panel 100 includes a display region 101 and a region 102.Here, the region 102 refers to a portion other than the display region101 in a top view of the display panel 100. The region 102 can also bereferred to as a non-display region.

For example, the display panel 100 may include the frame-like region 102that surrounds the display region 101 as illustrated in FIG. 2A.

FIGS. 2B to 2D specifically illustrate the structures of the region 102.The region 102 includes a region 110 transmitting visible light and aregion 120 blocking visible light. The region 110 transmitting visiblelight and the region 120 blocking visible light are each adjacent to thedisplay region 101. The region 110 transmitting visible light and theregion 120 blocking visible light may each be provided along part of theouter edge of the display region 101.

In the display panel 100 in FIG. 2B, the region 110 transmitting visiblelight is provided along one side of the display region 101. In thedisplay panel 100 in FIG. 2C, the region 110 transmitting visible lightis provided along two sides of the display region 101. The region 110transmitting visible light may be provided along three or more sides ofthe display region 101. The region 110 transmitting visible light ispreferably in contact with the display region 101 and provided so as toextend to end portions of the display panel as illustrated in FIGS. 2Bto 2D or the like.

In the display panel 100 in FIGS. 2B to 2D, the region 120 blockingvisible light is provided along two sides of the display region 101. Theregion 120 blocking visible light may be extended close to the endportions of the display panel.

Note that a region other than the region 110 transmitting visible lightand the region 120 blocking visible light in the region 102 illustratedin FIGS. 2B and 2C does not necessarily have a visible lighttransmitting property. For example, the region 110 transmitting visiblelight may be provided over the entire circumference of the display panelas illustrated in FIG. 2D. At least part of the region 110 transmittingvisible light may be adjacent to the display region 101. The region 120blocking visible light may be partly provided between the region 110transmitting visible light and the display region 101.

The display region 101 includes a plurality of pixels arranged in matrixand can display an image. One or more display elements are provided ineach pixel. As the display element, a light-emitting element such as anorganic EL element, an electrophoretic element, a display element withuse of a micro electro mechanical system (MEMS), a liquid crystalelement, or the like can be used, for example.

A material which transmits visible light is used for the region 110transmitting visible light. For example, the region 110 transmittingvisible light may include a substrate, a bonding layer, or the likeincluded in the display panel 100. The transmittance with respect tovisible light of the region 110 transmitting visible light is preferablyhigher because light extraction efficiency of the display panel underthe region 110 transmitting visible light can be increased. For example,in the region 110 transmitting visible light, the transmittance withrespect to light in a wavelength range of 450 nm to 700 nm is 70% ormore, preferably 80% or more, more preferably 90% or more on theaverage.

In the region 120 blocking visible light, for example, a wiringelectrically connected to the pixels (or display elements) included inthe display region 101 is provided. In addition to the wiring, drivercircuits (such as a scan line driver circuit and a signal line drivercircuit) for driving the pixels may be provided. Furthermore, the region120 blocking visible light may include a terminal electrically connectedto the FPC or the like (also referred to as a connection terminal), awiring electrically connected to the terminal, and the like.

Here, the width W of the region 110 transmitting visible lightillustrated in FIGS. 2B and 2C is preferably greater than or equal to0.5 mm and less than or equal to 150 mm, more preferably greater than orequal to 1 mm and less than or equal to 100 mm, still more preferablygreater than or equal to 2 mm and less than or equal to 50 mm. Theregion 110 transmitting visible light serves as a sealing region, and asthe width W of the region 110 transmitting visible light is larger, thedistance between the edge of the display panel 100 and the displayregion 101 can become longer, so that entry of an impurity such as waterinto the display region 101 from the outside can be suppressed. Notethat the width W of the region 110 transmitting visible lightcorresponds to the shortest distance between the display region 101 andthe edge of the display panel 100 in some cases.

For example, in the case where an organic EL element is used as thedisplay element, the width W of the region 110 transmitting visiblelight is set to be greater than or equal to 1 mm, whereby deteriorationof the organic EL element can be effectively suppressed, which leads toan improvement in reliability. Note that also in a part other than theregion 110 transmitting visible light, the distance between the edge ofthe display region 101 and the edge of the display panel 100 ispreferably in the above range.

The display device 10 in FIG. 1A includes a display panel 100 a, adisplay panel 100 b, and a display panel 100 c.

The display panel 100 b is placed so that part of the display panel 100b overlaps an upper side (a display surface side) of the display panel100 a. Specifically, the region 110 b transmitting visible light of thedisplay panel 100 b is provided to overlap the display region 101 a ofthe display panel 100 a. The region 120 b blocking visible light of thedisplay panel 100 b is provided so as not to overlap the display region101 a of the display panel 100 a. A display region 101 b of the displaypanel 100 b is provided to overlap a region 102 a of the display panel100 a and a region 120 a blocking visible light thereof.

Similarly, the display panel 100 c is placed so that part of the displaypanel 100 c overlaps an upper side (a display surface side) of thedisplay panel 100 b. Specifically, the region 110 c transmitting visiblelight of the display panel 100 c is provided to overlap the displayregion 101 b of the display panel 100 b. A region 120 c blocking visiblelight of the display panel 100 c is provided so as not to overlap thedisplay region 101 b of the display panel 100 b. A display region 101 cof the display panel 100 c is provided to overlap a region 102 b of thedisplay panel 100 b and a region 120 b blocking visible light of thedisplay panel 100 b.

The region 110 b transmitting visible light is provided to overlap thedisplay region 101 a; thus, a user of the display device 10 can visuallyrecognize the entire image of the display region 101 a even when thedisplay panel 100 b overlaps a display surface of the display panel 100a. Similarly, the region 110 c transmitting visible light is provided tooverlap the display region 101 b; thus, a user of the display device 10can visually recognize the entire image of the display region 101 b evenwhen the display panel 100 c overlaps a display surface of the displaypanel 100 b.

The display region 101 b of the display panel 100 b is provided tooverlap the upper sides of the region 102 a and the region 120 ablocking visible light, whereby a non-display region is not providedbetween the display region 101 a and the display region 101 b.Similarly, the display region 101 c of the display panel 100 c overlapsthe upper sides of the region 102 b and the region 120 b blockingvisible light, whereby a non-display region does not exist between thedisplay region 101 b and the display region 101 c. Therefore, a regionwhere the display region 101 a, the display region 101 b, and thedisplay region 101 c are placed seamlessly can serve as the displayregion 11 of the display device 10.

The display device 10 in FIGS. 1B and 1C includes the display panel 100a, the display panel 100 b, the display panel 100 c, and a display panel100 d.

In FIGS. 1B and 1C, short sides of the display panels 100 a and 100 boverlap with each other, so that part of the display region 101 a andpart of the region 110 b transmitting visible light overlap with eachother. The long sides of the display panels 100 a and 100 c overlap witheach other, so that part of the display region 101 a and part of theregion 110 c transmitting visible light overlap with each other.

In FIGS. 1B and 1C, part of the display region 101 b overlaps with partof the region 110 c transmitting visible light and part of a region 110d transmitting visible light. In addition, part of the display region101 c overlaps with part of the region 110 d transmitting visible light.

Therefore, as illustrated in FIG. 1B, a region where the display regions101 a to 101 d are placed seamlessly can serve as the display region 11of the display device 10.

Here, the display panel 100 preferably has flexibility. For example, apair of substrates included in the display panel 100 preferably hasflexibility.

Thus, as shown in FIGS. 1B and 1C, a region near an FPC 112 a of thedisplay panel 100 a can be bent so that part of the display panel 100 aand part of the FPC 112 a can be placed under the display region 101 bof the display panel 100 b adjacent to the FPC 112 a. As a result, theFPC 112 a can be placed without physical interference with the rearsurface of the display panel 100 b. Furthermore, when the display panel100 a and the display panel 100 b overlap and are fixed to each other,it is not necessary to consider the thickness of the FPC 112 a; thus,the difference in height between the top surface of the region 110 btransmitting visible light and the top surface of the display panel 100a can be reduced. This can make an end portion of the display panel 100b over the display region 101 a less noticeable.

Moreover, each display panel 100 has flexibility, whereby the displaypanel 100 b can be curved gently so that the top surface of the displayregion 101 b of the display panel 100 b and the top surface of thedisplay region 101 a of the display panel 100 a are equal to each otherin height. Thus, the heights of the display regions can be equal to eachother except in the vicinity of the region where the display panel 100 aand the display panel 100 b overlap each other, so that the displayquality of an image displayed on the display region 11 of the displaydevice 10 can be improved.

Although, the relation between the display panel 100 a and the displaypanel 100 b is taken as an example in the above description, the samecan apply to the relation between any other two adjacent display panels.

Furthermore, to reduce the step between two adjacent display panels 100,the thickness of the display panel 100 is preferably small. For example,the thickness of the display panel 100 is preferably less than or equalto 1 mm, further preferably less than or equal to 300 μm, still furtherpreferably less than or equal to 100 μm. The display panel is preferablythin because the thickness or weight of the whole display device canalso be reduced.

FIG. 3A is a top view of the display device 10 in FIGS. 1B and 1C whenseen from the display surface side.

Here, when the region 110 transmitting visible light of the displaypanel 100 does not have sufficiently high transmittance with respect tovisible light (e.g., light with a wavelength of greater than or equal to450 nm and less than or equal to 700 nm), luminance of a displayed imagemay be decreased depending on the number of display panels 100overlapping the display regions 101.

For example, in a region A in FIG. 3A, one display panel 100 c overlapsthe display region 101 a of the display panel 100 a. In a region B, thetwo display panels 100 (the display panels 100 c and 100 d) overlap thedisplay region 101 b of the display panel 100 b. In a region C, thethree display panels 100 (the display panels 100 b, 100 c and 100 d)overlap the display region 101 a of the display panel 100 a.

In this case, it is preferable that data of the displayed image becorrected so that the gray scale of the pixels is locally increaseddepending on the number of display panels 100 overlapping the displayregions 101. In this manner, a decrease in the display quality of theimage displayed on the display region 11 of the display device 10 can besuppressed.

Alternatively, the position of an end portion of the display panel 100placed on the upper side may be shifted from the positions of endportions of the other display panels 100, whereby the number of displaypanels 100 overlapping the display regions 101 of the lower displaypanels 100 can be reduced.

In FIG. 3B, the display panels 100 c and 100 d placed on the displaypanels 100 a and 100 b are shifted in one direction. Specifically, thedisplay panels 100 c and 100 d are relatively shifted from the displaypanels 100 a and 100 b in the X direction by the distance of the width Wof the region 110 transmitting visible light. At this time, there aretwo kinds of regions: a region D in which one display panel 100 overlapsthe display region 101, and a region E in which two display panels 100overlap the display region 101.

The display panel may be shifted in a direction perpendicular to the Xdirection (Y direction). In FIG. 3C, the display panels 100 b and 100 dare relatively shifted from the display panels 100 a and 100 c in the Ydirection by the distance of the width W of the region 110 transmittingvisible light.

In the case where the display panel 100 placed on the upper side isshifted from the display 100 placed on the lower side, the shape of thecontour of a region in which the display regions 101 of the displaypanels 100 are combined is different from a rectangular shape. Thus, inthe case where the shape of the display region 11 of the display device10 is set to a rectangular shape as illustrated in FIG. 3B or 3C, thedisplay device 10 may be driven so that no image is displayed on thedisplay regions 101 of the display panels 100 that are placed outsidethe display region 11. Here, considering the number of pixels in aregion where an image is not displayed, more pixels than the numberobtained by dividing the number of all the pixels in the rectangulardisplay region 11 by the number of display panels 100 may be provided inthe display region 101 of the display panel 100.

Although the distance of relative shift of each display panel 100 is setto an integral multiple of the width W of the region 110 transmittingvisible light in the above example, the distance is not limited thereto,and may be set as appropriate in consideration of the shape of thedisplay panel 100, the shape of the display region 11 of the displaydevice 10, in which the display panels 100 are combined, and the like.

FIGS. 4A to 4F and FIGS. 5A to 5F are examples of cross sectional viewsof the two display panels attached to each other.

In FIGS. 4A to 4D, a lower display panel includes the display region 101a, the region 110 a transmitting visible light, and the region 120 atransmitting visible light. The lower display panel is electricallyconnected to the FPC 112 a. A display panel on the upper side (on adisplay surface side) includes the display region 101 b, the region 110b transmitting visible light, and the region 120 b blocking visiblelight. The display panel on the upper side is electrically connected tothe FPC 112 b.

In FIG. 4A, the FPC 112 a and the FPC 112 b are connected to the displaysurface side (front surface) of the lower display panel and the displaysurface side of the of the upper display panel, respectively.

The display region 101 a overlaps with the region 110 b transmittingvisible light with the light-transmitting layer 103 providedtherebetween. Therefore, air can be prevented from entering between thedisplay region 101 a and the region 110 b transmitting visible light, sothat reflection at the interface due to a difference in refractive indexcan be suppressed.

Accordingly, luminance difference that occurs between part of thedisplay region 101 a that overlaps with the region 110 b transmittingvisible light and part of the display region 101 a that does not overlapwith the region 110 b transmitting visible light can be suppressed, sothat a seam between the display panels of the display device can behardly recognized by a user of the display device. In addition, displayunevenness or luminance unevenness of the display device can besuppressed.

The region 120 a blocking visible light and the FPC 112 a overlap thedisplay region 101 b. Therefore, a sufficient area of a non-displayregion can be secured and a seamless display region can be increased insize, so that a highly reliable large display device can be realized.

In FIG. 4B, the FPC 112 a and the FPC 112 b are connected to the surface(rear surface) side opposite to the display surface of the lower displaypanel and the surface (rear surface) side opposite to the displaysurface of the upper display panel, respectively.

As illustrated in FIG. 4B, the light-transmitting layer 103 may beprovided both between the display region 101 a and the region 110 btransmitting visible light and between the region 120 a transmittingvisible light and the display region 101 b.

When an FPC is connected to a rear surface side of the display panel,the end portion of the lower display panel can be attached to the rearsurface of the upper display panel; thus, the attachment area can beincreased and the mechanical strength of the attached portion can beincreased.

As illustrated in FIG. 4C, the light-transmitting layer 103 may overlapthe region of the display region 101 a not overlapping with the upperdisplay panel. Furthermore, the region 110 a transmitting visible lightand the light-transmitting layer 103 may overlap with each other.

As illustrated in FIG. 4D, the region of the upper display panel notoverlapping the display region 101 a and the light-transmitting layer103 may overlap with each other.

For example, as illustrated in FIG. 4E, the lower display panel mayinclude a substrate 151 a, a substrate 152 a, and an element layer 153a, and the upper display panel may include a substrate 151 b, asubstrate 152 b, and an element layer 153 b.

The element layer 153 a includes a region 155 a containing a displayelement and a region 156 a including a wiring electrically connected tothe display element. The wiring included in the region 156 a iselectrically connected to the FPC 112 a.

The element layer 153 b included in the upper display panel alsoincludes a region 155 b containing a display element and a region 156 bincluding a wiring electrically connected to the display element. Thewiring included in the region 156 b is electrically connected to the FPC112 b.

A light-transmitting layer 103 a is provided over the substrate 152 a.For example, a stack of the substrate 152 a and the light-transmittinglayer 103 a can be formed using the above-described attachment filmhaving a stack of an attachment layer and a base material. The substrate152 b and the light-transmitting layer 103 b can have a similarstructure to the stack of the substrate 152 a and the light-transmittinglayer 103 a.

Here, fine dirt such as dust in air is attached depending on a materialof the light-transmitting layer in some cases. In such a case, it ispreferable that the region of the display region 101 a not overlappingwith the upper display panel and the light-transmitting layer 103 do notoverlap with each other. This makes it possible to prevent uncleardisplay of the display device due to dirt or the like attached to thelight-transmitting layer 103.

As illustrated in FIG. 4F, the light-transmitting layer 103 a may be incontact with the substrate 151 a. For example, a stack of the substrate151 a and the light-transmitting layer 103 a can be formed with use ofthe above described attachment film having a stack of an attachmentlayer and a base material. The substrate 151 b and thelight-transmitting layer 103 b can have a similar structure to the stackof the substrate 151 a and the light-transmitting layer 103 a.

In the structure shown in FIG. 4F, the light-transmitting layer is notprovided on the outermost surface of the display surface of the displaydevice; thus, unclear display of the display device due to dirt or thelike attached to the light-transmitting layer 103 can be prevented. Inaddition, when a light-transmitting layer having attachability isprovided on the rear surface of the display device, the display devicecan be detachably attached to a desired portion by using a surface ofthe light-transmitting layer which is not in contact with the displaypanel.

Alternatively, as illustrated in FIGS. 5A and 5B, a resin layer 131which covers front surfaces of the display panel 100 a and the displaypanel 100 b may be provided. Specifically, the resin layer 131 ispreferably provided to cover the display regions of the display panels100 a and 100 b and a region where the display panel 100 a and thedisplay panel 100 b overlap.

By providing the resin layer 131 over the plurality of display panels100, the mechanical strength of the display device 10 can be increased.In addition, the resin layer 131 is formed to have a flat surface,whereby the display quality of an image displayed on the display region11 can be increased. For example, when a coating apparatus such as aslit coater, a curtain coater, a gravure coater, a roll coater, or aspin coater is used, the resin layer 131 with high flatness can beformed.

The refractive index of the resin layer 131 is preferably 0.8 to 1.2times as high as the refractive index of the substrate on the displaysurface side of the display panel 100, more preferably 0.9 times to 1.1times as high as the refractive index of the substrate on the displaysurface side of the display panel 100, and still more preferably 0.95 to1.15 times as high as the refractive index of the substrate on thedisplay surface side of the display panel 100. Light can be extractedoutside more efficiently as the difference in refractive index betweenthe display panel 100 and the resin layer 131 is smaller. In addition,the resin layer 131 with such a refractive index is provided to cover astep portion between the display panel 100 a and the display panel 100b, whereby the step portion is not easily recognized visually, and thedisplay quality of an image displayed on the display region 11 can beincreased.

The resin layer 131 is a layer that transmits visible light. As theresin layer 131, for example, an organic resin such as an epoxy resin,an aramid resin, an acrylic resin, a polyimide resin, a polyamide resin,or a polyamide-imide resin can be used.

Alternatively, as illustrated in FIGS. 5C and 5D, a protective substrate132 is preferably provided over the display device 10 with the resinlayer 131 provided therebetween. Here, the resin layer 131 may serve asa bonding layer for bonding the protective substrate 132 to the displaydevice 10. With the protective substrate 132, the surface of the displaydevice 10 can be protected, and moreover, the mechanical strength of thedisplay device 10 can be increased. For the protective substrate 132 ina region overlapping at least the display region 11, alight-transmitting material is used. Furthermore, the protectivesubstrate 132 in a region other than the region overlapping the displayregion 11 may have a light-blocking property not to be visuallyrecognized.

The protective substrate 132 may have a function of a touch panel. Inthe case where the display panel 100 is flexible and can be bent, theprotective substrate 132 is also preferably flexible.

Furthermore, a difference in refractive index between the protectivesubstrate 132 and the substrate on the display surface side of thedisplay panel 100 or the resin layer 131 is preferably less than orequal to 20%, further preferably less than or equal to 10%, stillfurther preferably less than or equal to 5%.

As the protective substrate 132, a plastic substrate that is formed as afilm can be used. Examples of the plastic substrate include polyesterresins such as polyethylene terephthalate (PET) and polyethylenenaphthalate (PEN), a polyacrylonitrile resin, a polyimide resin, apolymethyl methacrylate resin, a polycarbonate (PC) resin, apolyethersulfone (PES) resin, a polyamide resin (e.g., nylon, aramid), apolycycloolefin resin, a polystyrene resin, a polyamide imide resin, apolyvinyl chloride resin, polyetheretherketone (PEEK) resin, polysulfone(PSF) resin, polyetherimide (PEI) resin, polyarylate (PAR) resin,polybutylene terephthalate (PBT) resin, a polytetrafluoroethylene (PTFE)resin, and a silicone resin. A substrate in which a fibrous body isimpregnated with a resin (also referred to as prepreg) or a substratewhose coefficient of linear expansion is reduced by mixing an organicresin with an inorganic filler can also be used. Furthermore, theprotective substrate 132 is not limited to the resin film, and atransparent nonwoven fabric formed by processing pulp into a continuoussheet, a sheet including an artificial spider's thread fiber containingprotein called fibroin, a complex in which the transparent nonwovenfabric or the sheet and a resin are mixed, a stack of a resin film and anonwoven fabric containing a cellulose fiber whose fiber width is 4 nmor more and 100 nm or less, or a stack of a resin film and a sheetincluding an artificial spider's thread fiber may be used. Note that thedisplay device or the display panel of one embodiment of the presentinvention may be attached to an acrylic plate, a glass plate, a woodenplate, a metal plate, or the like. The display surface of the displaydevice or that of the display panel or the surface opposite to thedisplay surface thereof may be attached to these plates (in the casewhere the display surface is attached to any of these plates, a platetransmitting visible light is used). It is preferable that the displaydevice or the display panel be detachably attached to any of theseplates.

As the protective substrate 132, at least one of a polarizing plate, acircular polarizing plate, a retardation plate, an optical film, and thelike may be used.

As illustrated in FIG. 5E, resin layers 133 and protective substrates134 may be provided on surfaces opposite to the display surfaces of thedisplay panel 100 a and the display panel 100 b. When the substratesupporting the display panels is provided on the rear surfaces of thedisplay panels, unintended warping or bending of the display panels canbe suppressed, whereby the display surface is kept smooth. Thus, thedisplay quality of an image displayed on the display region 11 can beimproved.

Note that the resin layer 133 and the protective substrate 134, whichare provided on the side opposite to the display surface, do notnecessarily have a light-transmitting property, and a material whichabsorbs or reflects visible light may be used.

As illustrated in FIG. 5F, the resin layer 131 and the protectivesubstrate 132 may be provided on the front surfaces of the displaypanels, and the resin layer 133 and the protective substrate 134 may beprovided on the rear surface thereof. In this manner, the display panels100 a and 100 b are sandwiched between the two protective substrates,whereby the mechanical strength of the display device 10 can be furtherincreased.

It is preferable that the total thickness of the resin layer 131 and theprotective substrate 132 be approximately the same as that of the resinlayer 133 and the protective substrate 134. For example, it ispreferable that the thicknesses of the resin layers 131 and 133 aresubstantially equal to each other, and for the protective substrates 132and 134, materials having the same thickness be used. In that case, theplurality of display panels 100 can be located at the center of thestack in the thickness direction. For example, when the stack includingthe display panel 100 is bent, by locating the display panel 100 at thecenter in the thickness direction, stress in the lateral directionapplied to the display panel 100 by bending can be relieved, whichprevents the display panel 100 from being damaged.

In the case where the thickness of the resin layer and the protectivesubstrate differs between an end portion and a center of the displaydevice, for example, the total thickness of the resin layer 131 and theprotective substrate 132 and that of the resin layer 133 and theprotective substrate 134 can be compared in the same condition which isappropriately selected from conditions such as the average thickness,the largest thickness, the smallest thickness, or the like.

In FIG. 5F, the same material is preferably used for the resin layers131 and 133 because the manufacturing cost can be reduced. Similarly,the same material is preferably used for the protective substrates 132and 134 because the manufacturing cost can be reduced.

As illustrated in FIGS. 5E and 5F, an opening for extracting the FPC 112a is preferably provided in the resin layer 133 and the protectivesubstrate 134, which are located on the rear surface sides of thedisplay panels 100 a and 100 b. In particular, as illustrated in FIG.5F, by providing the resin layer 133 to cover part of the FPC 112 a, themechanical strength at a connection portion between the display panel100 a and the FPC 112 a can be increased, and defects such as separationof the FPC 112 a can be suppressed. Similarly, the resin layer 133 ispreferably provided to cover part of the FPC 112 b.

Next, a structure example of the display panel 100 is described. FIG. 6Ais an example of a top view in which a region P in FIG. 2C is enlarged,and FIG. 6B is an example of a top view in which a region Q in FIG. 2Cis enlarged.

As illustrated in FIG. 6A, in the display region 101, a plurality ofpixels 141 is arranged in matrix. In the case where the display panel100 capable of full color display with three colors of red, blue, andgreen is formed, each of the plurality of pixels 141 corresponds to asub-pixel capable of displaying any of the three colors. Alternatively,a sub-pixel capable of displaying white or yellow in addition to thethree colors may be provided. A region including the pixels 141corresponds to the display region 101.

A wiring 142 a and a wiring 142 b are electrically connected to onepixel 141. The plurality of wirings 142 a each intersects with thewiring 142 b, and is electrically connected to a circuit 143 a. Theplurality of wirings 142 b is electrically connected to a circuit 143 b.One of the circuits 143 a and 143 b can function as a scan line drivercircuit, and the other can function as a signal line driver circuit. Astructure without one of the circuits 143 a and 143 b or both of themmay be employed.

In FIG. 6A, a plurality of wirings 145 electrically connected to thecircuit 143 a or the circuit 143 b is provided. The wiring 145 iselectrically connected to an FPC 123 in an unillustrated region and hasa function of supplying a signal from the outside to the circuits 143 aand 143 b.

In FIG. 6A, a region including the circuit 143 a, the circuit 143 b, theplurality of wirings 145, and the like corresponds to the region 120blocking visible light.

In FIG. 6B, a region outside the pixel 141 provided closest to the endcorresponds to the region 110 transmitting visible light. The region 110transmitting visible light does not include the members blocking visiblelight, such as the pixel 141, the wiring 142 a, and the wiring 142 b.Note that in the case where part of the pixel 141, the wiring 142 a, orthe wiring 142 b transmits visible light, the part of the pixel 141, thewiring 142 a, or the wiring 142 b may be provided to extend to theregion 110 transmitting visible light.

In the case where the width W of the region 110 transmitting visiblelight varies depending on the display panel, or in the case where thewidth varies depending on the positions of the same display panel, theshortest length can be referred to as the width W. In FIG. 6B, thedistance between the pixel 141 and the end portion of the substrate(that is, the width W of the region 110 transmitting visible light) inthe vertical direction is the same as that in the horizontal direction,but one embodiment of the present invention is not limited thereto.

FIG. 6C is a cross-sectional view taken along line A1-A2 in FIG. 6B. Thedisplay panels 100 include a pair of substrates (a substrate 151 and asubstrate 152) transmitting visible light. The substrate 151 and thesubstrate 152 are bonded to each other with a bonding layer 154. Here,the substrate on which the pixel 141, the wiring 142 b, and the like areformed is referred to as the substrate 151.

As illustrated in FIGS. 6B and 6C, in the case where the pixel 141 ispositioned closest to the end of the display region 101, the width W ofthe region 110 transmitting visible light is the distance between theend portion of the substrate 151 or the substrate 152 and the endportion of the pixel 141.

Note that the end portion of the pixel 141 refers to the end portion ofthe member that is positioned closest to the end and blocks visiblelight in the pixel 141. Alternatively, in the case where alight-emitting element including a layer containing a light-emittingorganic compound between a pair of electrodes (also referred to as anorganic EL element) is used as the pixel 141, the end portion of thepixel 141 may be any of the end portion of the lower electrode, the endportion of the layer containing a light-emitting organic compound, andthe end portion of the upper electrode.

FIG. 7A is an example of a top view in which the region Q is enlarged,and the position of the wiring 142 a is different from that in FIG. 6B.FIG. 7B is a cross-sectional view taken along line B1-B2 in FIG. 7A, andFIG. 7C is a cross sectional view taken along line C1-C2 in FIG. 7A.

As illustrated in FIGS. 7A to 7C, in the case where the wiring 142 a ispositioned closest to the end of the display region 101, the width W ofthe region 110 transmitting visible light is the distance between theend portion of the substrate 151 or the substrate 152 and the endportion of the wiring 142 a. In the case where the wiring 142 atransmits visible light, the region 110 transmitting visible light mayinclude a region where the wiring 142 a is provided.

Here, in the case where the density of pixels provided in the displayregion 101 of the display panel 100 is high, misalignment may occur whenthe two display panels 100 are bonded.

FIGS. 8A to 8C show a positional relation between the display region 101a of the display panel 100 a provided on the lower side and the displayregion 101 b of the display panel 100 b provided on the upper side, seenfrom the display surface side. FIGS. 8A to 8C show the vicinities of thecorner portions of the display regions 101 a and 101 b. Part of thedisplay region 101 a is covered with the region 110 b transmittingvisible light.

FIG. 8A shows the case where adjacent pixels 141 a and 141 b arerelatively deviated in one direction (Y direction). The arrow in thedrawing denotes a direction in which the display panel 100 a is deviatedfrom the display panel 100 b.

FIG. 8B shows an example in which the adjacent pixels 141 a and 141 bare relatively deviated in a vertical direction and a horizontaldirection (X direction and Y direction).

In the examples of FIGS. 8A and 8B, the distances deviated in thevertical direction and the horizontal direction are each shorter thanthe length of one pixel. In this case, image data of the image displayedon either one of the display regions 101 a and 101 b is correcteddepending on the deviation distance, whereby the display quality can bemaintained.

Specifically, when the deviation makes the distance between the pixelssmaller, the data is corrected so that the gray level (luminance) of thepixels is low, and when the deviation makes the distance between thepixels larger, the data is corrected so that the gray level (luminance)of the pixels is high. Alternatively, when the two pixels overlap, thedata is corrected so that the pixel positioned on a lower side is notdriven and the image data is shifted by one column.

FIG. 8C shows an example in which the pixels 141 a and 141 b, whichshould be adjacent, are relatively deviated in one direction (Ydirection) by a distance of more than one pixel. When the deviation ofmore than one pixel occurs, the pixels are driven so that projectingpixels (pixels which are hatched) are not displayed. Note that the sameapplies to the case where the deviation direction is the X direction.

When the plurality of display panels 100 are bonded, in order tosuppress misalignment, each of the display panels 100 is preferablyprovided with an alignment marker or the like. Alternatively, aprojection and a depression may be formed on the surfaces of the displaypanels 100, and the projection and the depression may be attached toeach other in a region where the two display panels 100 overlap.

Furthermore, in consideration of alignment accuracy, it is preferablethat pixels more than the pixels to be used be placed in advance in thedisplay region 101 of the display panel 100. For example, it ispreferable that one or more, preferably three or more, furtherpreferably five or more extra pixel columns along either one or both ofa scan line and a signal line be provided in addition to the pixelcolumns used for display.

As described above, in the display device of one embodiment of thepresent invention, the display region of the display panel positioned onthe lower side and the region transmitting visible light of the displaypanel positioned on the upper side overlap with each other. Accordingly,a non-display region between the display regions of two overlappingdisplay panels can be reduced. Furthermore, the light-transmitting layerhaving a refractive index higher than that of air and transmittingvisible light is provided between the display region and the regiontransmitting visible light. In that case, air can be prevented fromentering between the display region and the region transmitting visiblelight, so that reflection at the interface due to a difference inrefractive index can be reduced. Thus, a large display device in which aseam between the display panels is hardly recognized and displayunevenness or luminance unevenness is suppressed can be obtained.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 2

In this embodiment, a light-emitting panel that can be used for thedisplay device of one embodiment of the present invention is describedwith reference to drawings.

Although a light-emitting panel including an organic EL element ismainly described in this embodiment as an example, a panel that can beused for the display device of one embodiment of the present inventionis not limited to this example.

Specific Example 1

FIG. 9A is a plan view of a light-emitting panel, and FIG. 9C is anexample of a cross-sectional view taken along dashed-dotted line A1-A2in FIG. 9A. FIG. 9C illustrates an example of a cross-sectional view ofthe region 110 transmitting visible light. The light-emitting paneldescribed in Specific Example 1 is a top-emission light-emitting panelusing a color filter method. In this embodiment, the light-emittingpanel can have a structure in which sub-pixels of three colors of red(R), green (G), and blue (B) express one color, a structure in whichsub-pixels of four colors of R, G, B, and white (W) express one color, astructure in which sub-pixels of four colors of R, G, B, and yellow (Y)express one color, or the like. There is no particular limitation on thecolor element and colors other than R, G, B, W, and Y may be used. Forexample, cyan, magenta, or the like may be used.

The light-emitting panel illustrated in FIG. 9A includes the region 110transmitting visible light, a light-emitting portion 804, a drivercircuit portion 806, and an FPC 808. The region 110 transmitting visiblelight is adjacent to the light-emitting portion 804, and is placed alongtwo sides of the light-emitting portion 804.

The light-emitting panel illustrated in FIG. 9C includes a substrate701, a bonding layer 703, an insulating layer 705, a plurality oftransistors, a conductive layer 857, an insulating layer 815, aninsulating layer 817, a plurality of light-emitting elements, aninsulating layer 821, a bonding layer 822, a coloring layer 845, alight-blocking layer 847, an insulating layer 715, a bonding layer 713,and a substrate 711. The bonding layer 822, the insulating layer 715,the bonding layer 713, and the substrate 711 transmit visible light.Light-emitting elements and transistors included in the light-emittingportion 804 and the driver circuit portion 806 are sealed with thesubstrate 701, the substrate 711, and the bonding layer 822.

The light-emitting portion 804 includes a transistor 820 and alight-emitting element 830 over the substrate 701 with the bonding layer703 and the insulating layer 705 provided therebetween. Thelight-emitting element 830 includes a lower electrode 831 over theinsulating layer 817, an EL layer 833 over the lower electrode 831, andan upper electrode 835 over the EL layer 833. The lower electrode 831 iselectrically connected to a source electrode or a drain electrode of thetransistor 820. An end portion of the lower electrode 831 is coveredwith the insulating layer 821. The lower electrode 831 preferablyreflects visible light. The upper electrode 835 transmits visible light.

The light-emitting portion 804 also includes the coloring layer 845overlapping with the light-emitting element 830 and the light-blockinglayer 847 overlapping with the insulating layer 821. The space betweenthe light-emitting element 830 and the coloring layer 845 is filled withthe bonding layer 822.

The insulating layer 815 has an effect of suppressing diffusion ofimpurities into a semiconductor included in the transistor. As theinsulating layer 817, an insulating layer having a planarizationfunction is preferably selected in order to reduce surface unevennessdue to the transistor.

The driver circuit portion 806 includes a plurality of transistors overthe substrate 701 with the bonding layer 703 and the insulating layer705 provided therebetween. In FIG. 9C, one of the transistors includedin the driver circuit portion 806 is illustrated.

The insulating layer 705 and the substrate 701 are attached to eachother with the bonding layer 703. The insulating layer 715 and thesubstrate 711 are attached to each other with the bonding layer 713. Theinsulating layer 705 and the insulating layer 715 are preferably highlyresistant to moisture, in which case impurities such as water can beprevented from entering the light-emitting element 830 or the transistor820, leading to higher reliability of the light-emitting panel.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal (e.g., a video signal, a clock signal, astart signal, and a reset signal) or a potential from the outside istransmitted to the driver circuit portion 806. Here, an example isdescribed in which an FPC 808 is provided as the external inputterminal. To prevent an increase in the number of fabrication steps, theconductive layer 857 is preferably formed using the same material andstep as the electrode or the wiring in the light-emitting portion or thedriver circuit portion. Here, an example in which the conductive layer857 is formed using the same material and step as the electrodesincluded in the transistor 820 is described.

In the light-emitting panel illustrated in FIG. 9C, the FPC 808 ispositioned over the substrate 711. A connector 825 is connected to theconductive layer 857 through an opening provided in the substrate 711,the bonding layer 713, the insulating layer 715, the bonding layer 822,the insulating layer 817, and the insulating layer 815. The connector825 is also connected to the FPC 808. The FPC 808 and the conductivelayer 857 are electrically connected to each other via the connector825. In the case where the conductive layer 857 overlaps with thesubstrate 711, the conductive layer 857, the connector 825, and the FPC808 can be electrically connected to one another by forming an openingin the substrate 711 (or using a substrate having an opening portion).

FIG. 20 is an example of a cross-sectional view of the display deviceincluding two light-emitting panels illustrated in FIG. 9B that overlapeach other. FIG. 20 illustrates the display region 101 a of the lowerlight-emitting panel (corresponding to the light-emitting portion 804illustrated in FIG. 9B), the region 120 a blocking visible light of thelower light-emitting panel (corresponding to the driver circuit portion806 or the like illustrated in FIG. 9B), the display region 101 b of anupper light-emitting panel (corresponding to the light-emitting portion804 illustrated in FIG. 9B), and the region 110 b transmitting visiblelight of the upper light-emitting panel (corresponding to the region 110transmitting visible light illustrated in FIG. 9B).

In the display device illustrated in FIG. 20, the light-emitting panelpositioned on the display surface side (upper side) includes the region110 b transmitting visible light adjacent to the display region 101 b.The display region 101 a of the lower light-emitting panel and theregion 110 b transmitting visible light of the upper light-emittingpanel overlap with each other. Therefore, a non-display region betweenthe display regions of the two light-emitting panels overlapping witheach other can be reduced or even removed. Accordingly, a large displaydevice in which a seam between light-emitting panels is hardlyrecognized by a user can be achieved.

The display device illustrated in FIG. 20 includes a light-transmittinglayer 103 having a refractive index higher than that of air andtransmitting visible light between the display region 101 a and theregion 110 b transmitting visible light. In that case, air can beprevented from entering between the display region 101 a and the region110 b transmitting visible light, so that the reflection at theinterface due to a difference in refractive index can be reduced. Inaddition, display unevenness or luminance unevenness of the displaydevice can be suppressed.

The light-transmitting layer 103 may overlap with the entire surface ofthe substrate 711 of the lower light-emitting panel or that of thesubstrate 701 of the upper light-emitting panel, or may overlap withonly the display region 101 a and the region 110 b transmitting visiblelight. In addition, the substrate 711 and the light-transmitting layer103 may be included in the region 120 a blocking visible light.

For example, the stack of the substrate 701 of the upper light-emittingpanel and the light-transmitting layer 103 can be formed of anattachment film having a stack of an attachment layer and a basematerial.

Specific Example 2

FIG. 9B is a plan view of the light-emitting panel, and FIG. 10A is anexample of a cross-sectional view taken along dashed-dotted line A3-A4in FIG. 9B. The light-emitting panel described in Specific Example 2 isa top-emission light-emitting panel using a color filter method, whichis different from that described in Specific Example 1. Portionsdifferent from those in Specific Example 1 will be described in detailhere and the descriptions of portions common to those in SpecificExample 1 will be omitted.

FIG. 9B illustrates an example where the region 110 transmitting visiblelight is provided along three sides of the light-emitting panel. Theregion 110 transmitting visible light along two sides among the three isadjacent to the light-emitting portion 804.

The light-emitting panel illustrated in FIG. 10A is different from thatin FIG. 9C in the following respects.

The light-emitting panel illustrated in FIG. 10A includes insulatinglayers 817 a and 817 b and a conductive layer 856 over the insulatinglayer 817 a. The source electrode or the drain electrode of thetransistor 820 and the lower electrode of the light-emitting element 830are electrically connected to each other through the conductive layer856.

The light-emitting panel illustrated in FIG. 10A includes a spacer 823over the insulating layer 821. The spacer 823 can adjust the distancebetween the substrate 701 and the substrate 711.

The light-emitting panel in FIG. 10A includes an overcoat 849 coveringthe coloring layer 845 and the light-blocking layer 847. The spacebetween the light-emitting element 830 and the overcoat 849 is filledwith the bonding layer 822.

In addition, in the light-emitting panel in FIG. 10A, the substrate 701differs from the substrate 711 in size. The FPC 808 is located over theinsulating layer 715 and does not overlap with the substrate 711. Theconnector 825 is connected to the conductive layer 857 through anopening provided in the insulating layer 715, the bonding layer 822, theinsulating layer 817, and the insulating layer 815. Since no openingneeds to be provided in the substrate 711, there is no limitation on thematerial of the substrate 711.

Note that as illustrated in FIG. 10B, the light-emitting element 830 mayinclude an optical adjustment layer 832 between the lower electrode 831and the EL layer 833. A light-transmitting conductive material ispreferably used for the optical adjustment layer 832. Owing to thecombination of a color filter (the coloring layer) and a microcavitystructure (the optical adjustment layer), light with high color puritycan be extracted from the display device of one embodiment of thepresent invention. The thickness of the optical adjustment layer may bevaried depending on the emission color of the sub-pixel.

Specific Example 3

FIG. 9B is a plan view of a light-emitting panel, and FIG. 10C is anexample of a cross-sectional view taken along dashed-dotted line A3-A4in FIG. 9B. The light-emitting panel described in Specific Example 3 isa top-emission light-emitting panel using a separate coloring method.

The light-emitting panel in FIG. 10C includes the substrate 701, thebonding layer 703, the insulating layer 705, a plurality of transistors,the conductive layer 857, the insulating layer 815, the insulating layer817, a plurality of light-emitting elements, the insulating layer 821,the spacer 823, the bonding layer 822, and the substrate 711. Thebonding layer 822 and the substrate 711 transmit visible light.

In the light-emitting panel illustrated in FIG. 10C, the connector 825is positioned over the insulating layer 815. The connector 825 isconnected to the conductive layer 857 through an opening provided in theinsulating layer 815. The connector 825 is also connected to the FPC808. The FPC 808 and the conductive layer 857 are electrically connectedto each other via the connector 825.

Specific Example 4

FIG. 9B is a plan view of a light-emitting panel, and FIG. 11A is anexample of a cross-sectional view taken along dashed-dotted line A3-A4in FIG. 9B. The light-emitting panel described in Specific Example 4 isa bottom-emission light-emitting panel using a color filter method.

The light-emitting panel in FIG. 11A includes the substrate 701, thebonding layer 703, the insulating layer 705, a plurality of transistors,the conductive layer 857, the insulating layer 815, the coloring layer845, the insulating layer 817 a, the insulating layer 817 b, theconductive layer 856, a plurality of light-emitting elements, theinsulating layer 821, the bonding layer 822, and the substrate 711. Thesubstrate 701, the bonding layer 703, the insulating layer 705, theinsulating layer 815, the insulating layer 817 a, and the insulatinglayer 817 b transmit visible light.

The light-emitting portion 804 includes the transistor 820, a transistor824, and the light-emitting element 830 over the substrate 701 with thebonding layer 703 and the insulating layer 705 provided therebetween.The light-emitting element 830 includes the lower electrode 831 over theinsulating layer 817 b, the EL layer 833 over the lower electrode 831,and the upper electrode 835 over the EL layer 833. The lower electrode831 is electrically connected to a source electrode or a drain electrodeof the transistor 820. An end portion of the lower electrode 831 iscovered with the insulating layer 821. The upper electrode 835preferably reflects visible light. The lower electrode 831 transmitsvisible light. The coloring layer 845 that overlaps with thelight-emitting element 830 can be provided anywhere; for example, thecoloring layer 845 may be provided between the insulating layers 817 aand 817 b or between the insulating layers 815 and 817 a.

The driver circuit portion 806 includes a plurality of transistors overthe substrate 701 with the bonding layer 703 and the insulating layer705 provided therebetween. In FIG. 11A, two of the transistors includedin the driver circuit portion 806 are illustrated.

The insulating layer 705 and the substrate 701 are attached to eachother with the bonding layer 703. The insulating layer 705 is preferablyhighly resistant to moisture, in which case impurities such as water canbe prevented from entering the light-emitting element 830, thetransistor 820, or the transistor 824 leading to higher reliability ofthe light-emitting panel.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal or a potential from the outside istransmitted to the driver circuit portion 806. Here, an example isdescribed in which an FPC 808 is provided as the external inputterminal. Here, an example is described in which the conductive layer857 is formed using the same material and the same step(s) as those ofthe conductive layer 856.

Specific Example 5

FIG. 11B illustrates an example of a light-emitting panel that isdifferent from those in Specific Examples 1 to 4.

A light-emitting panel in FIG. 11B includes the substrate 701, thebonding layer 703, the insulating layer 705, a conductive layer 814, aconductive layer 857 a, a conductive layer 857 b, the light-emittingelement 830, the insulating layer 821, the bonding layer 822, and thesubstrate 711.

The conductive layer 857 a and the conductive layer 857 b, which areexternal connection electrodes of the light-emitting panel, can each beelectrically connected to an FPC or the like.

The light-emitting element 830 includes the lower electrode 831, the ELlayer 833, and the upper electrode 835. An end portion of the lowerelectrode 831 is covered with the insulating layer 821. Thelight-emitting element 830 is a bottom-emission, top-emission, ordual-emission light-emitting element. An electrode, a substrate, aninsulating layer, and the like on the light extraction side transmitvisible light. The conductive layer 814 is electrically connected to thelower electrode 831.

The substrate through which light is extracted may have, as a lightextraction structure, a hemispherical lens, a micro lens array, a filmprovided with an uneven surface structure, a light diffusing film, orthe like. For example, a substrate having the light extraction structurecan be formed by bonding the above lens or film to a resin substratewith an adhesive or the like having substantially the same refractiveindex as the substrate or the lens or film.

The conductive layer 814 is preferably, though not necessarily, providedbecause voltage drop due to the resistance of the lower electrode 831can be prevented. In addition, for a similar purpose, a conductive layerelectrically connected to the upper electrode 835 may be provided overthe insulating layer 821, the EL layer 833, the upper electrode 835, orthe like.

The conductive layer 814 can be a single layer or a stacked layer formedusing a material selected from copper, titanium, tantalum, tungsten,molybdenum, chromium, neodymium, scandium, nickel, or aluminum; an alloymaterial containing any of these materials as its main component; or thelike. The thickness of the conductive layer 814 can be, for example,greater than or equal to 0.1 μm and less than or equal to 3 μm,preferably greater than or equal to 0.1 μm and less than or equal to 0.5μm.

<Examples of Materials>

Next, materials and the like that can be used for a light-emitting panelare described. Note that description on the components already describedin this specification is omitted in some cases.

For each of the substrates, a material such as glass, quartz, an organicresin, a metal, or an alloy can be used. The substrate on the side fromwhich light from the light-emitting element is extracted is formed usinga material which transmits the light.

It is particularly preferable to use a flexible substrate. For example,an organic resin; a glass material, a metal, or an alloy that is thinenough to have flexibility; or the like can be used.

An organic resin, which has a specific gravity smaller than that ofglass, is preferably used for the flexible substrate, in which case thelight-emitting panel can be more lightweight compared with the casewhere glass is used.

The substrates are preferred to be formed using a material with hightoughness. In that case, a light-emitting panel with high impactresistance that is less likely to be broken can be provided. Forexample, when an organic resin substrate, a thin metal substrate, or athin alloy substrate is used, the light-emitting panel can be lighterand more robust than the case where a glass substrate is used.

A metal material and an alloy material, which have high thermalconductivity, are preferred because they can easily conduct heat to thewhole substrate and accordingly can prevent a local temperature rise inthe light-emitting panel. The thickness of a substrate using a metalmaterial or an alloy material is preferably greater than or equal to 10μm and less than or equal to 200 μm, further preferably greater than orequal to 20 μm and less than or equal to 50 μm.

There is no particular limitation on a material of the metal substrateor the alloy substrate, but it is preferable to use, for example,aluminum, copper, nickel, a metal alloy such as an aluminum alloy orstainless steel.

Furthermore, when a material with high thermal emissivity is used forthe substrate, the surface temperature of the light-emitting panel canbe prevented from rising, leading to prevention of breakage or adecrease in reliability of the light-emitting panel. For example, thesubstrate may have a stacked-layer structure of a metal substrate and alayer with high thermal emissivity (e.g., the layer can be formed usinga metal oxide or a ceramic material).

Examples of materials having flexibility and a light-transmittingproperty include a material used for the protective substrate 132described in Embodiment 1.

The flexible substrate may have a stacked-layer structure in which ahard coat layer (such as a silicon nitride layer) by which a surface ofa light-emitting device is protected from damage, a layer (such as anaramid resin layer) which can disperse pressure, or the like is stackedover a layer of any of the above-mentioned materials.

The flexible substrate may be formed by stacking a plurality of layers.When a glass layer is used, a barrier property against water and oxygencan be improved and thus a reliable light-emitting panel can beprovided.

A flexible substrate in which a glass layer, a bonding layer, and anorganic resin layer are stacked from the side closer to a light-emittingelement is preferably used. The thickness of the glass layer is greaterthan or equal to 20 μm and less than or equal to 200 μm, preferablygreater than or equal to 25 μm and less than or equal to 100 μm. Withsuch a thickness, the glass layer can have both a high barrier propertyagainst water and oxygen and a high flexibility. The thickness of theorganic resin layer is greater than or equal to 10 μm and less than orequal to 200 μm, preferably greater than or equal to 20 μm and less thanor equal to 50 μm. Providing such organic resin layer outside the glasslayer, occurrence of a crack or a break in the glass layer can besuppressed and mechanical strength can be improved. With the substratethat includes such a composite material of a glass material and anorganic resin, a highly reliable and flexible light-emitting panel canbe provided.

Any of a variety of curable adhesives, e.g., light curable adhesivessuch as a UV curable adhesive, a reactive curable adhesive, a thermalcurable adhesive, and an anaerobic adhesive can be used for the adhesivelayer. Examples of these adhesives include an epoxy resin, an acrylicresin, a silicone resin, a phenol resin, a polyimide resin, an imideresin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB)resin, and an ethylene vinyl acetate (EVA) resin. In particular, amaterial with low moisture permeability, such as an epoxy resin, ispreferred. Alternatively, a two-component-mixture-type resin may beused. Further alternatively, an adhesive sheet or the like may be used.

Further, the resin may include a drying agent. For example, a substancethat adsorbs moisture by chemical adsorption, such as oxide of analkaline earth metal (e.g., calcium oxide or barium oxide), can be used.Alternatively, a substance that adsorbs moisture by physical adsorption,such as zeolite or silica gel, may be used. The drying agent ispreferably included because it can prevent an impurity such as moisturefrom entering the functional element, thereby improving the reliabilityof the light-emitting panel.

In addition, it is preferable to mix a filler with a high refractiveindex or light-scattering member into the resin, in which case theefficiency of light extraction from the light-emitting element can beimproved. For example, titanium oxide, barium oxide, zeolite, zirconium,or the like can be used.

Insulating films with high resistance to moisture are preferably usedfor the insulating layer 705 and the insulating layer 715.Alternatively, the insulating layer 705 and the insulating layer 715preferably have a function of preventing diffusion of impurities to alight-emitting element.

As an insulating film having an excellent moisture-proof property, afilm containing nitrogen and silicon (e.g., a silicon nitride film, asilicon nitride oxide film, or the like), a film containing nitrogen andaluminum (e.g., an aluminum nitride film or the like), or the like canbe used. Alternatively, a silicon oxide film, a silicon oxynitride film,an aluminum oxide film, or the like can be used.

For example, the moisture vapor transmission rate of the insulating filmhighly resistant to moisture is lower than or equal to 1×10⁻5[g/(m2·day)], preferably lower than or equal to 1×10⁻6 [g/(m2·day)],further preferably lower than or equal to 1×10⁻7 [g/(m2·day)], stillfurther preferably lower than or equal to 1×10⁻8 [g/(m2·day)].

In the light-emitting panel, it is necessary that at least one of theinsulating layers 705 and 715 transmit light emitted from thelight-emitting element. One of the insulating layers 705 and 715, whichtransmits light emitted from the light-emitting element, preferably hashigher average transmittance of light having a wavelength of greaterthan or equal to 400 nm and less than or equal to 800 nm than the other.

The insulating layers 705 and 715 each preferably include oxygen,nitrogen, and silicon. The insulating layers 705 and 715 each preferablyinclude, for example, silicon oxynitride. Moreover, the insulatinglayers 705 and 715 each preferably include silicon nitride or siliconnitride oxide. It is preferable that the insulating layers 705 and 715be each formed using a silicon oxynitride film and a silicon nitridefilm, which are in contact with each other. The silicon oxynitride filmand the silicon nitride film are alternately stacked so that antiphaseinterference occurs more often in a visible region, whereby the stackcan have higher transmittance of light in the visible region.

There is no particular limitation on the structure of the transistor inthe light-emitting panel. For example, a forward staggered transistor oran inverted staggered transistor may be used. Furthermore, a top-gatetransistor or a bottom-gate transistor may be used. A semiconductormaterial used for the transistors is not particularly limited, and forexample, silicon, germanium, or an organic semiconductor can be used.Alternatively, an oxide semiconductor containing at least one of indium,gallium, and zinc, such as an In—Ga—Zn-based metal oxide, may be used.

There is no particular limitation on the crystallinity of asemiconductor material used for the transistors, and an amorphoussemiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a polycrystalline semiconductor, asingle-crystal semiconductor, or a semiconductor partly includingcrystal regions) may be used. It is preferable that a semiconductorhaving crystallinity be used, in which case deterioration of thetransistor characteristics can be inhibited.

For stable characteristics of the transistor, a base film is preferablyprovided. The base film can be formed to have a single-layer structureor a stacked-layer structure using an inorganic insulating film such asa silicon oxide film, a silicon nitride film, a silicon oxynitride film,or a silicon nitride oxide film. The base film can be formed by asputtering method, a chemical vapor deposition (CVD) method (e.g., aplasma CVD method, a thermal CVD method, or a metal organic CVD (MOCVD)method), an atomic layer deposition (ALD) method, a coating method, aprinting method, or the like. Note that the base film is not necessarilyprovided. In each of the above structure examples, the insulating layer705 can serve as a base film of the transistor.

As the light-emitting element, a self-luminous element can be used, andan element whose luminance is controlled by current or voltage isincluded in the category of the light-emitting element. For example, alight-emitting diode (LED), an organic EL element, an inorganic ELelement, or the like can be used.

The light-emitting element may have any of a top emission structure, abottom emission structure, and a dual emission structure. A conductivefilm that transmits visible light is used as the electrode through whichlight is extracted. A conductive film that reflects visible light ispreferably used as the electrode through which light is not extracted.

The conductive film that transmits visible light can be formed using,for example, indium oxide, indium tin oxide (ITO), indium zinc oxide,zinc oxide (ZnO), or zinc oxide to which gallium is added.Alternatively, a film of a metal material such as gold, silver,platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron,cobalt, copper, palladium, or titanium; an alloy containing any of thesemetal materials; a nitride of any of these metal materials (e.g.,titanium nitride); or the like can be formed thin so as to have alight-transmitting property. Alternatively, a stacked film of any of theabove materials can be used as the conductive layer. For example, astacked film of ITO and an alloy of silver and magnesium is preferablyused, in which case conductivity can be increased. Furtheralternatively, graphene or the like may be used.

For the conductive film that reflects visible light, for example, ametal material, such as aluminum, gold, platinum, silver, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium or analloy including any of these metal materials can be used. Lanthanum,neodymium, germanium, or the like may be added to the metal material orthe alloy. Furthermore, an alloy containing aluminum (an aluminum alloy)such as an alloy of aluminum and titanium, an alloy of aluminum andnickel, an alloy of aluminum and neodymium, or an alloy of aluminum,nickel, and lanthanum (Al—Ni—La), or an alloy containing silver such asan alloy of silver and copper, an alloy of silver, palladium, and copper(Ag—Pd—Cu, also referred to as APC), or an alloy of silver and magnesiumcan be used for the conductive film. An alloy of silver and copper ispreferable because of its high heat resistance. Moreover, a metal filmor a metal oxide film is stacked on an aluminum alloy film, wherebyoxidation of the aluminum alloy film can be suppressed. Examples of amaterial for the metal film or the metal oxide film are titanium andtitanium oxide. Alternatively, the conductive film having a property oftransmitting visible light and a film containing any of the above metalmaterials may be stacked. For example, a stacked film of silver and ITOor a stacked film of an alloy of silver and magnesium and ITO can beused.

The electrodes may be formed separately by an evaporation method or asputtering method. Alternatively, a discharging method such as anink-jet method, a printing method such as a screen printing method, or aplating method may be used.

When a voltage higher than the threshold voltage of the light-emittingelement is applied between the lower electrode 831 and the upperelectrode 835, holes are injected to the EL layer 833 from the anodeside and electrons are injected to the EL layer 833 from the cathodeside. The injected electrons and holes are recombined in the EL layer833 and a light-emitting substance contained in the EL layer 833 emitslight.

The EL layer 833 includes at least a light-emitting layer. In additionto the light-emitting layer, the EL layer 833 may further include one ormore layers containing any of a substance with a high hole-injectionproperty, a substance with a high hole-transport property, ahole-blocking material, a substance with a high electron-transportproperty, a substance with a high electron-injection property, asubstance with a bipolar property (a substance with a high electron- andhole-transport property), and the like.

For the EL layer 833, either a low molecular compound or a highmolecular compound can be used, and an inorganic compound may also beused. Each of the layers included in the EL layer 833 can be formed byany of the following methods: an evaporation method (including a vacuumevaporation method), a transfer method, a printing method, an inkjetmethod, a coating method, and the like.

The light-emitting element 830 may contain two or more kinds oflight-emitting substances. Thus, for example, a light-emitting elementthat emits white light can be achieved. For example, a white emissioncan be obtained by selecting light-emitting substances so that two ormore kinds of light-emitting substances emit light of complementarycolors. A light-emitting substance that emits red (R) light, green (G)light, blue (B) light, yellow (Y) light, or orange (O) light or alight-emitting substance that emits light containing spectral componentsof two or more of R light, G light, and B light can be used, forexample. A light-emitting substance that emits blue light and alight-emitting substance that emits yellow light may be used, forexample. At this time, the emission spectrum of the light-emittingsubstance that emits yellow light preferably contains spectralcomponents of G light and R light. The emission spectrum of thelight-emitting element 830 preferably has two or more peaks in thewavelength range in a visible region (e.g., greater than or equal to 350nm and less than or equal to 750 nm or greater than or equal to 400 nmand less than or equal to 800 nm).

The EL layer 833 may include a plurality of light-emitting layers. Inthe EL layer 833, the plurality of light-emitting layers may be stackedin contact with one another or may be stacked with a separation layerprovided therebetween. The separation layer may be provided between afluorescent layer and a phosphorescent layer, for example.

The separation layer can be provided, for example, to prevent energytransfer by the Dexter mechanism (particularly triplet energy transfer)from a phosphorescent material or the like in an excited state which isgenerated in the phosphorescent layer to a fluorescent material or thelike in the fluorescent layer. The thickness of the separation layer maybe several nanometers. Specifically, the thickness of the separationlayer may be greater than or equal to 0.1 nm and less than or equal to20 nm, greater than or equal to 1 nm and less than or equal to 10 nm, orgreater than or equal to 1 nm and less than or equal to 5 nm. Theseparation layer contains a single material (preferably, a bipolarsubstance) or a plurality of materials (preferably, a hole-transportmaterial and an electron-transport material).

The separation layer may be formed using a material contained in alight-emitting layer in contact with the separation layer. Thisfacilitates the manufacture of the light-emitting element and reducesthe drive voltage. For example, in the case where the phosphorescentlayer includes a host material, an assist material, and a phosphorescentmaterial (guest material), the separation layer may be formed using thehost material and the assist material. In other words, the separationlayer includes a region not containing the phosphorescent material andthe phosphorescent layer includes a region containing the phosphorescentmaterial in the above structure. Accordingly, the separation layer andthe phosphorescent layer can be evaporated separately depending onwhether a phosphorescent material is used or not. With such a structure,the separation layer and the phosphorescent layer can be formed in thesame chamber. Thus, the manufacturing costs can be reduced.

Moreover, the light-emitting element 830 may be a single elementincluding one EL layer or a tandem element in which EL layers arestacked with a charge generation layer provided therebetween.

The light-emitting element is preferably provided between a pair ofinsulating films having an excellent moisture-proof property. In thatcase, entry of an impurity such as moisture into the light-emittingelement can be inhibited, leading to inhibition of a decrease in thereliability of the light-emitting device. Specifically, the use of aninsulating film having high resistance to moisture for the insulatinglayer 705 and the insulating layer 715 allows the light-emitting elementto be located between a pair of insulating films having high resistanceto moisture, by which decrease in reliability of the light-emittingdevice can be prevented.

As the insulating layer 815, for example, an inorganic insulating filmsuch as a silicon oxide film, a silicon oxynitride film, or an aluminumoxide film can be used. For example, as the insulating layer 817, theinsulating layer 817 a, and the insulating layer 817 b, an organicmaterial such as polyimide, acrylic, polyamide, polyimide amide, or abenzocyclobutene-based resin can be used. Alternatively, alow-dielectric constant material (a low-k material) or the like can beused. Furthermore, each insulating layer may be formed by stacking aplurality of insulating films.

The insulating layer 821 is formed using an organic insulating materialor an inorganic insulating material. As the resin, for example, apolyimide resin, a polyamide resin, an acrylic resin, a siloxane resin,an epoxy resin, or a phenol resin can be used. It is particularlypreferable that the insulating layer 821 be formed to have an openingover the lower electrode 831 and an inclined side wall with curvature,using a photosensitive resin material.

There is no particular limitation on the method for forming theinsulating layer 821; a photolithography method, a sputtering method, anevaporation method, a droplet discharging method (e.g., an inkjetmethod), a printing method (e.g., a screen printing method or an off-setprinting method), or the like may be used.

The spacer 823 can be formed using an inorganic insulating material, anorganic insulating material, a metal material, or the like. As theinorganic insulating material and the organic insulating material, forexample, a variety of materials that can be used for the insulatinglayer can be used. As the metal material, titanium, aluminum, or thelike can be used. When the spacer 823 containing a conductive materialis electrically connected to the upper electrode 835, a potential dropdue to the resistance of the upper electrode 835 can be inhibited. Thespacer 823 may have either a tapered shape or an inverse tapered shape.

For example, a conductive layer functioning as an electrode or a wiringof the transistor, an auxiliary electrode of the light-emitting element,or the like, which is used for the light-emitting device, can be formedto have a single-layer structure or a stacked-layer structure using anyof metal materials such as molybdenum, titanium, chromium, tantalum,tungsten, aluminum, copper, neodymium, and scandium, and an alloymaterial containing any of these elements. Alternatively, the conductivelayer may be formed using a conductive metal oxide. As the conductivemetal oxide, indium oxide (e.g., In₂O₃), tin oxide (e.g., SnO₂), ZnO,ITO, indium zinc oxide (e.g., In₂O₃—ZnO), or any of these metal oxidematerials in which silicon oxide is contained can be used.

The coloring layer is a colored layer that transmits light in a specificwavelength range. For example, a color filter for transmitting light ina red, green, blue, or yellow wavelength range can be used. Eachcoloring layer is formed in a desired position with any of variousmaterials by a printing method, an inkjet method, an etching methodusing a photolithography method, or the like. In a white sub-pixel, aresin such as a transparent resin may be provided so as to overlap withthe light-emitting element.

The light-blocking layer is provided between the adjacent coloringlayers. The light-blocking layer blocks light emitted from an adjacentlight-emitting element to inhibit color mixture between adjacentlight-emitting elements. Here, the coloring layer is provided such thatits end portion overlaps with the light-blocking layer, whereby lightleakage can be reduced. As the light-blocking layer, a material that canblock light from the light-emitting element can be used; for example, ablack matrix is formed using a resin material containing a metalmaterial, pigment, or dye. Note that it is preferable to provide thelight-blocking layer in a region other than the light-emitting portion,such as a driver circuit portion, in which case undesired leakage ofguided light or the like can be inhibited.

Furthermore, an overcoat covering the coloring layer and thelight-blocking layer may be provided. The overcoat can prevent animpurity and the like contained in the coloring layer from beingdiffused into the light-emitting element. The overcoat is formed with amaterial that transmits light emitted from the light-emitting element;for example, an inorganic insulating film such as a silicon nitride filmor a silicon oxide film, an organic insulating film such as an acrylicfilm or a polyimide film can be used, and further, a stacked-layerstructure of an organic insulating film and an inorganic insulating filmmay be employed.

In the case where upper surfaces of the coloring layer and thelight-blocking layer are coated with a material of the bonding layer, amaterial which has high wettability with respect to the material of thebonding layer is preferably used as the material of the overcoat. Forexample, an oxide conductive film such as an ITO film or a metal filmsuch as an Ag film which is thin enough to transmit light is preferablyused as the overcoat.

As the connector, any of a variety of anisotropic conductive films(ACF), anisotropic conductive pastes (ACP), and the like can be used.

As described above, a variety of panels such as a light-emitting panel,a display panel, and a touch panel can be used in the display device ofone embodiment of the present invention.

Note that the light-emitting panel of one embodiment of the presentinvention may be used as a display device or as a lighting panel. Forexample, it may be used as a light source such as a backlight or a frontlight, that is, a lighting device for a display panel.

As described above, with a light-emitting panel including a regiontransmitting visible light described in this embodiment, a large displaydevice in which a seam between light-emitting panels is hardlyrecognized and display unevenness is suppressed can be obtained.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 3

In this embodiment, a flexible display panel that can be used for thedisplay device of one embodiment of the present invention is describedwith reference to drawings. Note that the above description can bereferred to for the components of a touch panel, which are similar tothose of the light-emitting panel described in Embodiment 2. Although atouch panel including a light-emitting element is described in thisembodiment as an example, one embodiment of the present invention is notlimited to this example.

Structure Example 1

FIG. 12A is a top view of the touch panel. FIG. 12B is a cross-sectionalview taken along dashed-dotted line A-B and dashed-dotted line C-D inFIG. 12A. FIG. 12C is a cross-sectional view taken along dashed-dottedline E-F in FIG. 12A.

A touch panel 390 illustrated in FIG. 12A includes a display portion 301(serving also as an input portion), a scan line driver circuit 303 g(1),an imaging pixel driver circuit 303 g(2), an image signal line drivercircuit 303 s(1), and an imaging signal line driver circuit 303 s(2).

The display portion 301 includes a plurality of pixels 302 and aplurality of imaging pixels 308.

The pixel 302 includes a plurality of sub-pixels. Each sub-pixelincludes a light-emitting element and a pixel circuit.

The pixel circuits can supply electric power for driving thelight-emitting element. The pixel circuits are electrically connected towirings through which selection signals are supplied. The pixel circuitsare also electrically connected to wirings through which image signalsare supplied.

The scan line driver circuit 303 g(1) can supply selection signals tothe pixels 302.

The image signal line driver circuit 303 s(1) can supply image signalsto the pixels 302.

A touch sensor can be formed using the imaging pixels 308. Specifically,the imaging pixels 308 can sense a touch of a finger or the like on thedisplay portion 301.

The imaging pixels 308 include photoelectric conversion elements andimaging pixel circuits.

The imaging pixel circuits can drive photoelectric conversion elements.The imaging pixel circuits are electrically connected to wirings throughwhich control signals are supplied. The imaging pixel circuits are alsoelectrically connected to wirings through which power supply potentialsare supplied.

Examples of the control signal include a signal for selecting an imagingpixel circuit from which a recorded imaging signal is read, a signal forinitializing an imaging pixel circuit, and a signal for determining thetime for an imaging pixel circuit to sense light.

The imaging pixel driver circuit 303 g(2) can supply control signals tothe imaging pixels 308.

The imaging signal line driver circuit 303 s(2) can read out imagingsignals.

As illustrated in FIGS. 12B and 12C, the touch panel 390 includes thesubstrate 701, the bonding layer 703, the insulating layer 705, thesubstrate 711, the bonding layer 713, and the insulating layer 715. Thesubstrates 701 and 711 are bonded to each other with a bonding layer360.

The substrate 701 and the insulating layer 705 are attached to eachother with the bonding layer 703. The substrate 711 and the insulatinglayer 715 are attached to each other with the bonding layer 713.

Embodiment 2 can be referred to for materials used for the substrates,the bonding layers, and the insulating layers.

Each of the pixels 302 includes the sub-pixel 302R, a sub-pixel 302G,and a sub-pixel 302B (FIG. 12C). The sub-pixel 302R includes alight-emitting module 380R, the sub-pixel 302G includes a light-emittingmodule 380G, and the sub-pixel 302B includes a light-emitting module380B.

For example, the sub-pixel 302R includes the light-emitting element 350Rand the pixel circuit. The pixel circuit includes a transistor 302 tthat can supply electric power to the light-emitting element 350R.Furthermore, the light-emitting module 380R includes the light-emittingelement 350R and an optical element (e.g., a coloring layer 367R thattransmits red light).

The light-emitting element 350R includes a lower electrode 351R, an ELlayer 353, and an upper electrode 352, which are stacked in this order(see FIG. 12C).

The EL layer 353 includes a first EL layer 353 a, an intermediate layer354, and a second EL layer 353 b, which are stacked in this order.

Note that a microcavity structure can be provided for the light-emittingmodule 380R so that light with a specific wavelength can be efficientlyextracted. Specifically, an EL layer may be provided between a film thatreflects visible light and a film that partly reflects and partlytransmits visible light, which are provided so that light with aspecific wavelength can be efficiently extracted.

The light-emitting module 380R, for example, includes a bonding layer360 that is in contact with the light-emitting element 350R and thecoloring layer 367R.

The coloring layer 367R is positioned in a region overlapping with thelight-emitting element 350R. Accordingly, part of light emitted from thelight-emitting element 350R passes through the bonding layer 360 andthrough the coloring layer 367R and is emitted to the outside of thelight-emitting module 380R as indicated by an arrow in FIG. 12C.

The touch panel 390 includes a light-blocking layer 367BM. Thelight-blocking layer 367BM is provided so as to surround the coloringlayer (e.g., the coloring layer 367R).

The touch panel 390 includes an anti-reflective layer 367 p positionedin a region overlapping with the display portion 301. As theanti-reflective layer 367 p, a circular polarizing plate can be used,for example.

The touch panel 390 includes an insulating layer 321. The insulatinglayer 321 covers the transistor 302 t and the like. Note that theinsulating layer 321 can be used as a layer for planarizing unevennesscaused by the pixel circuits and the imaging pixel circuits. Aninsulating layer that can inhibit diffusion of impurities to thetransistor 302 t and the like can be used as the insulating layer 321.

The touch panel 390 includes a partition 328 that overlaps with an endportion of the lower electrode 351R. A spacer 329 that controls thedistance between the substrate 701 and the substrate 711 is provided onthe partition 328.

The image signal line driver circuit 303 s(1) includes a transistor 303t and a capacitor 303 c. Note that the driver circuit can be formed inthe same process and over the same substrate as those of the pixelcircuits. As illustrated in FIG. 12B, the transistor 303 t may include asecond gate 304 over the insulating layer 321. The second gate 304 maybe electrically connected to a gate of the transistor 303 t, ordifferent potentials may be supplied to these gates. Alternatively, ifnecessary, the second gate 304 may be provided for a transistor 308 t,the transistor 302 t, or the like.

The imaging pixels 308 each include a photoelectric conversion element308 p and an imaging pixel circuit. The imaging pixel circuit can senselight received by the photoelectric conversion element 308 p. Theimaging pixel circuit includes the transistor 308 t.

For example, a PIN photodiode can be used as the photoelectricconversion element 308 p.

The touch panel 390 includes a wiring 311 through which a signal issupplied. The wiring 311 is provided with a terminal 319. An FPC 309through which a signal such as an image signal or a synchronizationsignal is supplied is electrically connected to the terminal 319. Aprinted wiring board (PWB) may be attached to the FPC 309.

Note that transistors such as the transistors 302 t, 303 t, and 308 tcan be formed in the same process. Alternatively, the transistors may beformed in different processes.

Structure Example 2

FIGS. 13A and 13B are perspective views of a touch panel 505. FIGS. 13Aand 13B illustrate only main components for simplicity. FIGS. 14A to 14Care each a cross-sectional view taken along the dashed-dotted line X1-X2in FIG. 13A.

As illustrated in FIGS. 13A and 13B, the touch panel 505 includes adisplay portion 501, the scan line driver circuit 303 g(1), a touchsensor 595, and the like. Furthermore, the touch panel 505 includes thesubstrate 701, the substrate 711, and a substrate 590.

The touch panel 505 includes a plurality of pixels and a plurality ofwirings 311. The plurality of wirings 311 can supply signals to thepixels. The plurality of wirings 311 are arranged to a peripheralportion of the substrate 701, and part of the plurality of wirings 311form the terminal 319. The terminal 319 is electrically connected to anFPC 509(1).

The touch panel 505 includes the touch sensor 595 and a plurality ofwirings 598. The plurality of wirings 598 are electrically connected tothe touch sensor 595. The plurality of wirings 598 are arranged to aperipheral portion of the substrate 590, and part of the plurality ofwirings 598 form a terminal. The terminal is electrically connected toan FPC 509(2). Note that in FIG. 13B, electrodes, wirings, and the likeof the touch sensor 595 provided on the back side of the substrate 590(the side facing the substrate 701) are indicated by solid lines forclarity.

As the touch sensor 595, for example, a capacitive touch sensor can beused. Examples of the capacitive touch sensor include a surfacecapacitive touch sensor and a projected capacitive touch sensor. Anexample of using a projected capacitive touch sensor is described here.

Examples of the projected capacitive touch sensor are a self capacitivetouch sensor and a mutual capacitive touch sensor, which differ mainlyin the driving method. The use of a mutual capacitive type is preferablebecause multiple points can be sensed simultaneously.

Note that a variety of sensors that can sense the closeness or thecontact of a sensing target such as a finger can be used as the touchsensor 595.

The projected capacitive touch sensor 595 includes electrodes 591 andelectrodes 592. The electrodes 591 are electrically connected to any ofthe plurality of wirings 598, and the electrodes 592 are electricallyconnected to any of the other wirings 598.

The electrodes 592 each have a shape of a plurality of quadranglesarranged in one direction with one corner of a quadrangle connected toone corner of another quadrangle as illustrated in FIGS. 13A and 13B.

The electrodes 591 each have a quadrangular shape and are arranged in adirection intersecting with the direction in which the electrodes 592extend. Note that the plurality of electrodes 591 is not necessarilyarranged in the direction orthogonal to one electrode 592 and may bearranged to intersect with one electrode 592 at an angle of less than 90degrees.

The wiring 594 intersects with the electrode 592. A wiring 594electrically connects two electrodes 591 between which the electrode 592is positioned. The intersecting area of the electrode 592 and the wiring594 is preferably as small as possible. Such a structure allows areduction in the area of a region where the electrodes are not provided,reducing unevenness in transmittance. As a result, unevenness inluminance of light from the touch sensor 595 can be reduced.

Note that the shapes of the electrodes 591 and the electrodes 592 arenot limited to the above-mentioned shapes and can be any of a variety ofshapes. For example, the plurality of electrodes 591 may be provided sothat space between the electrodes 591 are reduced as much as possible,and a plurality of electrodes 592 may be provided with an insulatinglayer sandwiched between the electrodes 591 and the electrodes 592 andmay be spaced apart from each other to form a region not overlappingwith the electrodes 591. In that case, between two adjacent electrodes592, it is preferable to provide a dummy electrode which is electricallyinsulated from these electrodes, whereby the area of a region having adifferent transmittance can be reduced.

As illustrated in FIG. 14A, the touch panel 505 includes the substrate701, the bonding layer 703, the insulating layer 705, the substrate 711,the bonding layer 713, and the insulating layer 715. The substrates 701and 711 are bonded to each other with a bonding layer 360.

A bonding layer 597 attaches the substrate 590 to the substrate 711 sothat the touch sensor 595 overlaps with the display portion 501. Thebonding layer 597 has a light-transmitting property.

The electrodes 591 and the electrodes 592 are formed using alight-transmitting conductive material. As a light-transmittingconductive material, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded can be used. A film including graphene may be used as well. Thefilm including graphene can be formed, for example, by reducing a filmincluding graphene oxide. As a reducing method, heating or the like canbe employed.

The resistance of a material used for conductive films such as theelectrodes 591, the electrodes 592, and the wiring 594, i.e., a wiringand an electrode in the touch panel, is preferably low. Examples of thematerial include ITO, indium zinc oxide, ZnO, silver, copper, aluminum,a carbon nanotube, and graphene. Alternatively, a metal nanowireincluding a number of conductors with an extremely small width (forexample, a diameter of several nanometers) may be used. Examples of sucha metal nanowire include an Ag nanowire, a Cu nanowire, and an Alnanowire. In the case of using an Ag nanowire, light transmittance of89% or more and a sheet resistance of 40 ohm/square or more and 100ohm/square or less can be achieved. Note that a metal nanowire, a carbonnanotube, graphene, or the like may be used for an electrode of thedisplay element, e.g., a pixel electrode or a common electrode becauseof its high transmittance.

The electrodes 591 and the electrodes 592 may be formed by depositing alight-transmitting conductive material on the substrate 590 by asputtering method and then removing an unnecessary portion by a varietyof patterning technique such as photolithography.

The electrodes 591 and the electrodes 592 are covered with an insulatinglayer 593. Furthermore, openings reaching the electrodes 591 are formedin the insulating layer 593, and the wiring 594 electrically connectsthe adjacent electrodes 591. A light-transmitting conductive materialcan be favorably used as the wiring 594 because the aperture ratio ofthe touch panel can be increased. Moreover, a material with higherconductivity than the conductivities of the electrodes 591 and 592 canbe favorably used as the wiring 594 because electric resistance can bereduced.

Note that an insulating layer that covers the insulating layer 593 andthe wiring 594 may be provided to protect the touch sensor 595.

Furthermore, a connection layer 599 electrically connects the wiring 598to the FPC 509(2).

The display portion 501 includes a plurality of pixels arranged in amatrix. Each pixel has the same structure as Structure Example 1; thus,description is omitted.

Any of various kinds of transistors can be used in the touch panel. Astructure in the case of using bottom-gate transistors is illustrated inFIGS. 14A and 14B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 302 t andthe transistor 303 t illustrated in FIG. 14A.

For example, a semiconductor layer containing polycrystalline siliconthat is obtained by crystallization process such as laser annealing canbe used in the transistor 302 t and the transistor 303 t illustrated inFIG. 14B.

A structure in the case of using top-gate transistors is illustrated inFIG. 14C.

For example, a semiconductor layer containing polycrystalline silicon, asingle crystal silicon film that is transferred from a single crystalsilicon substrate, or the like can be used in the transistor 302 t andthe transistor 303 t illustrated in FIG. 14C.

Structure Example 3

FIGS. 15A to 15C are cross-sectional views of a touch panel 505B. Thetouch panel 505B described in this embodiment is different from theinput-output device 505 in Structure Example 2 in that received imagedata is displayed on the side where the transistors are provided andthat the touch sensor is provided on the substrate 701 side of thedisplay portion. Different structures will be described in detail below,and the above description is referred to for the other similarstructures.

The coloring layer 367R is positioned in a region overlapping with thelight-emitting element 350R. The light-emitting element 350R illustratedin FIG. 15A emits light to the side where the transistor 302 t isprovided. Accordingly, part of light emitted from the light-emittingelement 350R passes through the coloring layer 367R and is emitted tothe outside of the light-emitting module 380R as indicated by an arrowin FIG. 15A.

The touch panel 505B includes the light-blocking layer 367BM on thelight extraction side. The light-blocking layer 367BM is provided so asto surround the coloring layer (e.g., the coloring layer 367R).

The touch sensor 595 is provided not on the substrate 711 side but onthe substrate 701 side (see FIG. 15A).

The bonding layer 597 attaches the substrate 590 to the substrate 701 sothat the touch sensor 595 overlaps with the display portion. The bondinglayer 597 has a light-transmitting property.

Note that a structure in the case of using bottom-gate transistors inthe display portion 501 is illustrated in FIGS. 15A and 15B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 302 t andthe transistor 303 t illustrated in FIG. 15A.

For example, a semiconductor layer containing polycrystalline siliconcan be used in the transistor 302 t and the transistor 303 t illustratedin FIG. 15B.

A structure in the case of using top-gate transistors is illustrated inFIG. 15C.

For example, a semiconductor layer containing polycrystalline silicon, atransferred single crystal silicon film, or the like can be used in thetransistor 302 t and the transistor 303 t illustrated in FIG. 15C.

Structure Example 4

As illustrated in FIG. 16, the touch panel 500TP includes a displayportion 500 and an input portion 600 that overlap each other. FIG. 17 isa cross-sectional view taken along the dashed-dotted line Z1-Z2 in FIG.16.

Components of the touch panel 500TP are described below. Note that theseunits can not be clearly distinguished and one unit also serves asanother unit or include part of another unit in some cases. Note thatthe touch panel 500TP in which the input portion 600 overlaps with thedisplay portion 500 is also referred to as a touch panel.

The input portion 600 includes a plurality of sensing units 602 arrangedin a matrix. The input portion 600 also includes a selection signal lineG1, a control line RES, a signal line DL, and the like.

The selection signal line G1 and the control line RES are electricallyconnected to the plurality of sensing units 602 that are arranged in therow direction (indicated by the arrow R in FIG. 16). The signal line DLis electrically connected to the plurality of sensing units 602 that arearranged in the column direction (indicated by the arrow C in FIG. 16).

The sensing unit 602 senses an object that is close thereto or incontact therewith and supplies a sensing signal. For example, thesensing unit 602 senses, for example, capacitance, illuminance, magneticforce, electric waves, or pressure and supplies data based on the sensedphysical quantity. Specifically, a capacitor, a photoelectric conversionelement, a magnetic sensing element, a piezoelectric element, aresonator, or the like can be used as the sensing element.

The sensing unit 602 senses, for example, a change in capacitancebetween the sensing unit 602 and an object close thereto or an object incontact therewith.

Note that when an object having a dielectric constant higher than thatof air, such as a finger, comes close to a conductive film in air, thecapacitance between the finger and the conductive film changes. Thesensing unit 602 can sense the capacitance change and supply sensingdata.

For example, distribution of charge occurs between the conductive filmand the capacitor owing to the change in the electrostatic capacitance,so that the voltage across the capacitor is changed. This voltage changecan be used as the sensing signal.

The sensing unit 602 is provided with a sensor circuit. The sensorcircuit is electrically connected to the selection signal line G1, thecontrol line RES, the signal line DL, or the like.

The sensor circuit includes a transistor, a sensor element, and/or thelike. For example, a conductive film and a capacitor electricallyconnected to the conductive film can be used for the sensor circuit. Acapacitor and a transistor electrically connected to the capacitor canalso be used for the sensor circuit.

For example, a capacitor 650 including an insulating layer 653, and afirst electrode 651 and a second electrode 652 between which theinsulating layer 653 is provided can be used for the sensor circuit (seeFIG. 17A). Specifically, the voltage between the electrodes of thecapacitor 650 changes when an object approaches the conductive filmwhich is electrically connected to one electrode of the capacitor 650.

The sensing unit 602 includes a switch that can be turned on or off inaccordance with a control signal. For example, a transistor M12 can beused as the switch.

A transistor which amplifies a sensing signal can be used in the sensingunit 602.

Transistors manufactured through the same process can be used as thetransistor that amplifies a sensing signal and the switch. This allowsthe input portion 600 to be provided through a simplified process.

The sensing unit includes a plurality of window portions 667 arranged ina matrix. The window portions 667 transmit visible light. Alight-blocking layer BM may be provided between the window portions 667.

The touch panel 500TP is provided in a position overlapping with thewindow portion 667 in the touch panel 500TP. The coloring layertransmits light of a predetermined color. Note that the coloring layercan be referred to as a color filter. For example, a coloring layer 367Btransmitting blue light, a coloring layer 367G transmitting green light,and a coloring layer 367R transmitting red light can be used.Alternatively, a coloring layer transmitting yellow light or white lightmay be used.

The display portion 500 includes the plurality of pixels 302 arranged ina matrix. The pixel 302 is positioned so as to overlap with the windowportions 667 of the input portion 600. The pixels 302 may be arranged athigher resolution than the sensing units 602. Each pixel has the samestructure as Structure Example 1; thus, description is omitted.

The touch panel 500TP includes the input portion 600 that includes theplurality of sensing units 602 arranged in a matrix and the windowportions 667 transmitting visible light, the display portion 500 thatincludes the plurality of pixels 302 overlapping with the windowportions 667, and the coloring layers between the window portions 667and the pixels 302. Each of the sensing units includes a switch that canreduce interference in another sensing unit.

Thus, sensing data obtained by each sensor unit can be supplied togetherwith the positional information of the sensor unit. In addition, sensingdata can be supplied in relation to the positional data of the pixel fordisplaying an image. In addition, the sensor unit which does not supplythe sensing data is not electrically connected to a signal line, wherebyinterference with the sensor unit which supplies a sensing signal can bereduced. Consequently, the input-output device 500TP that is highlyconvenient or highly reliable can be provided.

For example, the input portion 600 of the touch panel 500TP can sensesensing data and supply the sensing data together with the positionaldata. Specifically, a user of the touch panel 500TP can make a varietyof gestures (e.g., tap, drag, swipe, and pinch-in operation) using, as apointer, his/her finger or the like on the input portion 600.

The input portion 600 can sense a finger or the like that comes close toor is in contact with the input portion 600 and supply sensing dataincluding a sensed position, path, or the like.

An arithmetic unit determines whether or not supplied data satisfies apredetermined condition on the basis of a program or the like andexecutes an instruction associated with a predetermined gesture.

Thus, a user of the input portion 600 can make the predetermined gesturewith his/her finger or the like and make the arithmetic unit execute aninstruction associated with the predetermined gesture.

For example, first, the input portion 600 of the input-output device500TP selects one sensing unit X from the plurality of sensing unitsthat can supply sensing data to one signal line. Then, electricalcontinuity between the signal line and the sensing units other than thesensing unit X is not established. This can reduce interference of theother sensing units in the sensing unit X.

Specifically, interference of sensing elements of the other sensingunits in a sensing element of the sensing unit X can be reduced.

For example, in the case where a capacitor and a conductive film towhich one electrode of the capacitor is electrically connected are usedfor the sensing element, interference of the potentials of theconductive films of the other sensing units in the potential of theconductive film of the sensing unit X can be reduced.

Thus, the touch panel 500TP can drive the sensing unit and supplysensing data independently of its size. The touch panel 500TP can have avariety of sizes, for example, ranging from a size for a hand-helddevice to a size for an electronic blackboard.

The touch panel 500TP can be folded and unfolded. Even in the case whereinterference of the other sensing units in the sensing unit X isdifferent between the folded state and the unfolded state, the sensingunit can be driven and sensing data can be supplied without dependenceon the state of the touch panel 500TP.

The display portion 500 of the touch panel 500TP can be supplied withdisplay data. For example, an arithmetic unit can supply the displaydata.

In addition to the above structure, the touch panel 500TP can have thefollowing structure.

The touch panel 500TP may include a driver circuit 603 g or a drivercircuit 603 d. In addition, the touch panel 500TP may be electricallyconnected to an FPC1.

The driver circuit 603 g can supply selection signals at predeterminedtimings, for example. Specifically, the driver circuit 603 g suppliesselection signals to the selection signal lines G1 row by row in apredetermined order. Any of a variety of circuits can be used as thedriver circuit 603 g. For example, a shift register, a flip flopcircuit, a combination circuit, or the like can be used.

The driver circuit 603 d supplies sensing data on the basis of a sensingsignal supplied from the sensing unit 602. Any of a variety of circuitscan be used as the driver circuit 603 d. For example, a circuit that canform a source follower circuit or a current mirror circuit by beingelectrically connected to the sensing circuit in the sensing unit can beused as the driver circuit 603 d. In addition, an analog-to-digitalconverter circuit that converts a sensing signal into a digital signalmay be provided in the driver circuit 603 d.

The FPC1 supplies a timing signal, a power supply potential, or the likeand is supplied with a sensing signal.

The touch panel 500TP may include a driver circuit 503 g, a drivercircuit 503 s, a wiring 311, and a terminal 319. In addition, the touchpanel 500TP (or driver circuit) may be electrically connected to anFPC2.

In addition, a protective layer 670 that prevents damage and protectsthe input-output device 500TP may be provided. For example, a ceramiccoat layer or a hard coat layer can be used as the protective layer 670.Specifically, a layer containing aluminum oxide or a UV curable resincan be used.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 4

In this embodiment, electronic devices and lighting devices of oneembodiment of the present invention will be described with reference todrawings.

Examples of electronic devices include a television set (also referredto as a television or a television receiver), a monitor of a computer orthe like, a digital camera, a digital video camera, a digital photoframe, a mobile phone (also referred to as a mobile phone device), aportable game machine, a portable information terminal, an audioreproducing device, a large game machine such as a pinball machine, andthe like.

The electronic device or the lighting device of one embodiment of thepresent invention has flexibility and therefore can be incorporatedalong a curved inside/outside wall surface of a house or a building or acurved interior/exterior surface of a car.

Furthermore, the electronic device of one embodiment of the presentinvention may include a secondary battery. It is preferable that thesecondary battery be capable of being charged by non-contact powertransmission.

Examples of the secondary battery include a lithium ion secondarybattery such as a lithium polymer battery using a gel electrolyte(lithium ion polymer battery), a nickel-hydride battery, anickel-cadmium battery, an organic radical battery, a lead-acid battery,an air secondary battery, a nickel-zinc battery, and a silver-zincbattery.

The electronic device of one embodiment of the present invention mayinclude an antenna. When a signal is received by the antenna, theelectronic device can display an image, data, or the like on a displayportion. When the electronic device includes a secondary battery, theantenna may be used for contactless power transmission.

In the display device of one embodiment of the present invention, byincreasing the number of display panels, the area of the display regioncan be increased unlimitedly. Thus, the display device can be favorablyused for applications such as digital signage and a PID. Furthermore, bychanging the arrangement of the display panels, the contour of thedisplay device of one embodiment of the present invention can have anyof a variety of shapes.

FIG. 18A shows an example in which the display device 10 of oneembodiment of the present invention is provided for a column 15 and awall 16. A flexible display panel is used as the display panel 100included in the display device 10, whereby the display device 10 can beplaced along a curved surface.

Here, in particular, in the case where the display device of oneembodiment of the present invention is used in digital signage and aPID, it is preferable to use a touch panel in a display panel because adevice with such a structure can be operated by viewers intuitively aswell as displaying a still or moving image on a display region.Alternatively, in the case where the display device of one embodiment ofthe present invention is used for providing information such as routeinformation and traffic information, usability can be enhanced byintuitive operation. In the case of providing the display device on thewalls of buildings, public facilities, and the like, a touch panel isnot necessarily used in the display panel.

FIGS. 18B to 18E illustrate an example of an electronic device includingthe display portion 7000 with a curved surface. The display surface ofthe display portion 7000 is bent, and images can be displayed on thebent display surface. The display portion 7000 may be flexible.

The display portion 7000 of each of the electronic devices illustratedin FIGS. 18B to 18E can be formed using the display device of oneembodiment of the present invention.

FIG. 18B illustrates an example of a mobile phone. A mobile phone 7100includes a housing 7101, the display portion 7000, operation buttons7103, an external connection port 7104, a speaker 7105, a microphone7106, and the like.

The mobile phone 7100 illustrated in FIG. 18B includes a touch sensor inthe display portion 7000. Moreover, operations such as making a call andinputting a letter can be performed by touch on the display portion 7000with a finger, a stylus, or the like.

With the operation buttons 7103, power ON or OFF can be switched. Inaddition, types of images displayed on the display portion 7000 can beswitched; switching images from a mail creation screen to a main menuscreen, for example.

FIG. 18C illustrates an example of a television set. In a television set7200, the display portion 7000 is incorporated into the housing 7201.Here, the housing 7201 is supported by a stand 7203.

The television set 7200 illustrated in FIG. 18C can be operated with anoperation switch of the housing 7201 or a separate remote controller7211. Furthermore, the display portion 7000 may include a touch sensor.The display portion 7000 can be performed by touching the displayportion with a finger or the like. Furthermore, the remote controller7211 may be provided with a display portion for displaying data outputfrom the remote controller 7211. With operation keys or a touch panel ofthe remote controller 7211, channels and volume can be controlled andimages displayed on the display portion 7000 can be controlled.

Note that the television set 7200 is provided with a receiver, a modem,and the like. A general television broadcast can be received with thereceiver. Further, when the television set is connected to acommunication network with or without wires via the modem, one-way (froma transmitter to a receiver) or two-way (between a transmitter and areceiver or between receivers) data communication can be performed.

FIG. 18D illustrates an example of a portable information terminal. Aportable information terminal 7300 includes a housing 7301 and thedisplay portion 7000. Each of the portable information terminals mayalso include an operation button, an external connection port, aspeaker, a microphone, an antenna, a battery, or the like. The displayportion 7000 is provided with a touch sensor. An operation of theportable information terminal 7300 can be performed by touching thedisplay portion 7000 with a finger, a stylus, or the like.

FIG. 18D is a perspective view of the portable information terminal7300. FIG. 18E is a top view of the portable information terminal 7300.

Each of the portable information terminals illustrated in thisembodiment functions as, for example, one or more of a telephone set, anotebook, and an information browsing system. Specifically, each of theportable information terminals can be used as a smartphone. Each of theportable information terminals illustrated in this embodiment is capableof executing a variety of applications such as mobile phone calls,e-mailing, reading and editing texts, music reproduction, Internetcommunication, and a computer game, for example.

The portable information terminal 7300 can display characters and imageinformation on its plurality of surfaces. For example, as illustrated inFIG. 18D, three operation buttons 7302 can be displayed on one surface,and information 7303 indicated by a rectangle can be displayed onanother surface. FIGS. 18D and 18E illustrate an example in whichinformation is displayed at the top of the portable informationterminal. Alternatively, information may be displayed on the side of theportable information terminal. Information may also be displayed onthree or more surfaces of the portable information terminal.

Examples of the information include notification from a socialnetworking service (SNS), display indicating reception of an e-mail oran incoming call, the title of an e-mail or the like, the sender of ane-mail or the like, the date, the time, remaining battery, and thereception strength of an antenna. Alternatively, the operation button,an icon, or the like may be displayed in place of the information.

For example, a user of the portable information terminal 7300 can seethe display (here, the information 7303) with the portable informationterminal 7300 put in a breast pocket of his/her clothes.

Specifically, a caller's phone number, name, or the like of an incomingcall is displayed in a position that can be seen from above the portableinformation terminal 7300. Thus, the user can see the display withouttaking out the portable information terminal 7300 from the pocket anddecide whether to answer the call.

FIG. 18F illustrates an example of a lighting device having a curvedlight-emitting portion.

The light-emitting portion included in the lighting devices illustratedin FIG. 18F can be manufactured using the display device of oneembodiment of the present invention.

A lighting device 7400 illustrated in FIG. 18F includes a light-emittingportion 7402 having a wave-shaped light-emitting surface, which is agood-design lighting device.

The light-emitting portion included in the lighting device 7400 may beflexible. The light-emitting portion may be fixed on a plastic member, amovable frame, or the like so that an emission surface of thelight-emitting portion can be bent freely depending on the intended use.

The lighting device 7400 includes a stage 7401 provided with anoperation switch 7403 and a light-emitting portion supported by thestage 7401.

Note that although the lighting device in which the light-emittingportion is supported by the stage is described as an example here, ahousing provided with a light-emitting portion can be fixed on a ceilingor suspended from a ceiling. Since the light-emitting surface can becurved, the light-emitting surface is curved to have a depressed shape,whereby a particular region can be brightly illuminated, or thelight-emitting surface is curved to have a projecting shape, whereby awhole room can be brightly illuminated.

FIGS. 19A1, 19A2, 19B, 19C, 19D, 19E, 19F, 19G, 19H, and 19I eachillustrate an example of a portable information terminal including adisplay portion 7001 having flexibility.

The display portion 7001 is manufactured using the display device of oneembodiment of the present invention. For example, a display device thatcan be bent with a radius of curvature of greater than or equal to 0.01mm and less than or equal to 150 mm can be used. The display portion7001 may include a touch sensor so that the portable informationterminal can be operated by touching the display portion 7001 with afinger or the like.

FIGS. 19A1 and 19A2 are a perspective view and a cross-sectional view,respectively, illustrating an example of the portable informationterminal. A portable information terminal 7500 includes a housing 7501,the display portion 7001, a display portion pull 7502, operation buttons7503, and the like.

The portable information terminal 7500 includes a rolled flexibledisplay portion 7001 in the housing 7501.

The portable information terminal 7500 can receive a video signal with acontrol portion incorporated therein and can display the received videoon the display portion 7001. The portable information terminal 7500incorporates a battery. A terminal portion for connecting a connectormay be included in the housing 7501 so that a video signal or power canbe directly supplied from the outside with a wiring.

By pressing the operation buttons 7503, power ON/OFF, switching ofdisplayed videos, and the like can be performed. Although FIGS. 19A1,19A2, and 19B illustrate an example where the operation buttons 7503 arepositioned on a side surface of the portable information terminal 7500,one embodiment of the present invention is not limited thereto. Theoperation buttons 7503 may be placed on a display surface (a frontsurface) or a rear surface of the portable information terminal 7500.

FIG. 19B illustrates the portable information terminal 7500 in a statewhere the display portion 7001 is pulled out. Videos can be displayed onthe display portion 7001 in this state. In addition, the portableinformation terminal 7500 may perform different displays in the statewhere part of the display portion 7001 is rolled as shown in FIG. 19A1and in the state where the display portion 7001 is pulled out with thedisplay portion pull 7502 as shown in FIG. 19B. For example, in thestate shown in FIG. 19A1, the rolled portion of the display portion 7001is put in a non-display state, which results in a reduction in powerconsumption of the portable information terminal 7500.

Note that a reinforcement frame may be provided for a side portion ofthe display portion 7001 so that the display portion 7001 has a flatdisplay surface when pulled out.

Note that in addition to this structure, a speaker may be provided forthe housing so that sound is output with an audio signal receivedtogether with a video signal.

FIGS. 19C to 19E illustrate an example of a foldable portableinformation terminal. FIG. 19C illustrates a portable informationterminal 7600 that is opened. FIG. 19D illustrates the portableinformation terminal 7600 that is being opened or being folded. FIG. 19Eillustrates the portable information terminal 7600 that is folded. Theportable information terminal 7600 is highly portable when folded, andis highly browsable when opened because of a seamless large displayarea.

A display portion 7001 is supported by three housings 7601 joinedtogether by hinges 7602. By folding the portable information terminal7600 at a connection portion between two housings 7601 with the hinges7602, the portable information terminal 7600 can be reversibly changedin shape from an opened state to a folded state.

FIGS. 19F and 19G illustrate an example of a foldable portableinformation terminal. FIG. 19F illustrates a portable informationterminal 7650 that is folded so that the display portion 7001 is on theinside. FIG. 19G illustrates the portable information terminal 7650 thatis folded so that the display portion 7001 is on the outside. Theportable information terminal 7650 includes the display portion 7001 anda non-display portion 7651. When the portable information terminal 7650is not used, the portable information terminal 7650 is folded so thatthe display portion 7001 is on the inside, whereby the display portion7001 can be prevented from being contaminated or damaged.

FIG. 19H illustrates an example of a flexible portable informationterminal. The portable information terminal 7700 includes a housing 7701and the display portion 7001. In addition, the portable informationterminal 7700 may include buttons 7703 a and 7703 b which serve as inputmeans, speakers 7704 a and 7704 b which serve as sound output means, anexternal connection port 7705, a microphone 7706, or the like. Aflexible battery 7709 can be mounted on the portable informationterminal 7700. The battery 7709 may be arranged to overlap with thedisplay portion 7001, for example.

The housing 7701, the display portion 7001, the battery 7709 areflexible. Thus, it is easy to curve the portable information terminal7700 into a desired shape or to twist the portable information terminal7700. For example, the portable information terminal 7700 can be curvedso that the display portion 7001 is on the inside or in the outside. Theportable information terminal 7700 can be used in a rolled state. Sincethe housing 7701 and the display portion 7001 can be transformed freelyin this manner, the portable information terminal 7700 is less likely tobe broken even when the portable information terminal 7700 falls down orexternal stress is applied to the portable information terminal 7700.

The portable information terminal 7700 can be used effectively invarious situations because the portable information terminal 7700 islightweight. For example, the portable information terminal 7700 can beused in the state where the upper portion of the housing 7701 issuspended by a clip or the like, or in the state where the housing 7701is fixed to a wall by magnets or the like.

FIG. 19I illustrates an example of a wrist-watch-type portableinformation terminal. The portable information terminal 7800 includes aband 7801, the display portion 7001, an input-output terminal 7802,operation buttons 7803, or the like. The band 7801 has a function of ahousing. A flexible battery 7805 can be mounted on the portableinformation terminal 7800. The battery 7805 may overlap with the displayportion 7001 and the band 7801, for example.

The band 7801, the display portion 7001, and the battery 7805 haveflexibility. Thus, the portable information terminal 7800 can be easilycurved to have a desired shape.

With the operation button 7803, a variety of functions such as timesetting, ON/OFF of the power, ON/OFF of wireless communication, settingand cancellation of manner mode, and setting and cancellation of powersaving mode can be performed. For example, the functions of theoperation button 7803 can be set freely by the operating systemincorporated in the portable information terminal 7800.

By touching an icon 7804 displayed on the display portion 7001 with afinger or the like, application can be started.

The portable information terminal 7800 can employ near fieldcommunication that is a communication method based on an existingcommunication standard. In that case, for example, mutual communicationbetween the portable information terminal 7800 and a headset capable ofwireless communication can be performed, and thus hands-free calling ispossible.

The portable information terminal 7800 may include the input-outputterminal 7802. In the case where the input-output terminal 7802 isincluded, data can be directly transmitted to and received from anotherinformation terminal via a connector. Charging through the input-outputterminal 7802 is also possible. Note that charging of the portableinformation terminal described as an example in this embodiment can beperformed by non-contact power transmission without using theinput-output terminal.

This embodiment can be combined with any other embodiment asappropriate.

Example 1

In this example, the results of manufacturing the display device of oneembodiment of the present invention are described. The method formanufacturing the display device used in this example is similar to thatfor manufacturing a Japanese traditional roof with tiles (kawara inJapanese). Thus, a multidisplay manufactured by overlapping a pluralityof display panels as in the display device manufactured in this exampleis referred to as a “kawara-type multidisplay” in some cases.

FIGS. 21A and 21B illustrate a display device manufactured in thisexample. FIG. 21A is a photograph of the opposite side to the displaysurface of the display device. FIG. 21B is a photograph of the displaysurface side of the display device displaying an image.

The display device illustrated in FIGS. 21A and 21B includes fourdisplay panels arranged in a matrix of two rows and two columns.Specifically, the display device includes the display panels 100 a, 100b, 100 c, and 100 d.

FIG. 22A is a schematic view of the display panel. A light-emittingportion 250 in the display panel has a size of 3.4 inches diagonal,960×540×RGB effective pixels, a resolution of 326 ppi, and an apertureratio of 44.4%. The display panel includes a demultiplexer (DeMUX) 253serving as a source driver. In addition, the display panel also includesa scan driver 255. The display panel is an active matrix organic ELdisplay, and a pixel circuit includes three transistors and a capacitor.Two sides of the light-emitting portion 250 are in contact with a region251 transmitting visible light. A lead wiring 257 is provided along theother two sides.

FIG. 21C is a cross-sectional schematic view of the display panels 100 aand 100 b attached to each other in the display device.

The display device illustrated in FIGS. 21A to 21C is different from thedisplay device illustrated in FIG. 4F in that a bonding layer 157 isincluded and a light-transmitting layer is provided on the displaysurface side of the display panel.

Each of the display panels has light-transmitting layers on both thedisplay surface and a surface opposite to the display surface. Forexample, as illustrated in FIG. 21C, the display panel 100 a has alight-transmitting layer 103 a 1 on the display surface side and alight-transmitting layer 103 a 2 on the surface opposite to the displaysurface. The display panel 100 b has a light-transmitting layer 103 b 1on the display surface side and a light-transmitting layer 103 b 2 onthe surface opposite to the display surface. In this example, anattachment film having a stack of an attachment layer and a basematerial was used as each of the light-transmitting layers.

Each of the display panels was formed by attaching a substrate and anelement layer with a bonding layer. For example, as illustrated in FIG.21C, the substrate 151 a, the substrate 152 a, the substrate 151 b, andthe substrate 152 b are attached to the element layer 153 a, the elementlayer 153 a, the element layer 153 b, and the element layer 153 brespectively, with the bonding layer 157.

The display device in this example is formed by overlapping four displaypanels so that a non-display region between display regions is madesmall. Specifically, the region transmitting visible light of onedisplay panel overlaps the display region of another display panel withthe light-transmitting layer provided therebetween. Accordingly, a largedisplay device in which a seam between the display panels is hardlyrecognized by a user can be obtained (see FIG. 21B).

Because the display panel has attachment layers on both the displaysurface and the surface opposite to the display surface, both sides ofthe display device can be attached to or fixed to a flat surface. Forexample, the surface opposite to the display surface of the displaydevice can be attached to a wall. In addition, the display surface ofthe display device can be attached to a transparent plate such as aglass substrate. The attachment layer can prevent the display surface ofthe display device from being damaged and the display device from beingbent, whereby display visibility can be improved.

The four display panels have flexibility. Thus, as illustrate in FIGS.21A and 21C, a region near the FPC 112 a of the display panel 100 a canbe bent so that part of the display panel 100 a and part of the FPC 112a can be placed under the display region of the display panel 100 badjacent to the FPC 112 a. As a result, the FPC 112 a can be placedwithout physical interference with the rear surface of the display panel100 b.

Since the attachment film having a stack of an attachment layer and abase material is used, each of the display panels can be detachablyattached to another display panel included in the display device.

The structure of the display panels 100 a to 100 d illustrated in FIG.21A corresponds to that of the light-emitting panel illustrated in FIGS.10A and 10B except the following points. First, each of the displaypanels 100 a to 100 d does not include the insulating layer 817 b andthe conductive layer 856, and the source electrode or the drainelectrode of the transistor 820 and the lower electrode 831 of thelight-emitting element 830 are directly connected to each other. Second,each of the display panels 100 a to 100 d does not include thelight-blocking layer 847. For the structure of the light-emittingelement 830 of each of the display panels 100 a to 100 d, FIG. 10B canbe referred to.

In this example, as the light-emitting element, a tandem (stack) organicEL element emitting white light is used. The light-emitting element hasa top emission structure. Light from the light-emitting element isextracted outside through a color filter.

As the transistor, a transistor including a c-axis aligned crystallineoxide semiconductor (CAAC-OS) was used. Unlike amorphous semiconductor,the CAAC-OS has few defect states, so that the reliability of thetransistor can be improved. Moreover, since the CAAC-OS does not have agrain boundary, a stable and uniform film can be formed over a largearea, and stress that is caused by bending a flexible display panel or adisplay device does not easily make a crack in a CAAC-OS film.

A CAAC-OS is a crystalline oxide semiconductor having c-axis alignmentof crystals in a direction substantially perpendicular to the filmsurface. It has been found that oxide semiconductors have a variety ofcrystal structures other than a single-crystal structure. An example ofsuch structures is a nano-crystal (nc) structure, which is an aggregateof nanoscale microcrystals. The crystallinity of the CAAC-OS structureis lower than that of a single-crystal structure and higher than that ofan nc structure.

In this example, a channel-etched transistor including an In—Ga—Zn-basedoxide was used. The transistor was fabricated over a glass substrate ata process temperature lower than 500° C.

Here, FIG. 22B illustrates the stacked-layer structure of the region 110transmitting visible light in the display panel used in this example.

As illustrated in FIG. 22B, in the region 110 transmitting visiblelight, the substrate 701, the bonding layer 703, the insulating layer705, a gate insulating layer 813, the insulating layer 815, the bondinglayer 822, the insulating layer 715, the bonding layer 713, and thesubstrate 711 are stacked in this order. As the visible lighttransmittance of the region 110 transmitting visible light is higher,the efficiency of light extraction of the display device can beincreased. In this example, the kind and the thickness of an inorganicinsulating film in the stacked-layer structure were optimized by meansof an optical simulation to improve the transmittance with respect tolight.

At the optical simulation, in order to ensure the favorablecharacteristics (or reliability) of the transistor, the kinds and thethicknesses of the gate insulating layer 813 and the insulating layer815 serving as a protective film of the transistor were not changed.Since only the region 110 transmitting visible light of these films canbe opened, formation of only part of a layer included in the gateinsulating layer 813 or the insulating layer 815 was allowed.

Specifically, although the insulating layer 815 has a stacked-layerstructure of a silicon oxynitride film and a silicon nitride film in thelight-emitting portion or the like, the silicon nitride film was notprovided in the region 110 transmitting visible light based on thecalculation results.

The display panel in this example was formed in such a manner that alayer to be separated was formed over a formation substrate with aseparation layer provided therebetween, separated from the formationsubstrate, and then transferred to another substrate.

Therefore, to secure the separability, the kinds and the thicknesses ofa layer in contact with the separation layer included in the insulatinglayer 705 (a layer included in the insulating layer 705 which is incontact with the bonding layer 703 in the display panel) and a layer incontact with the separation layer included in the insulating layer 715(a layer included in the insulating layer 715 which is in contact withthe bonding layer 713 in the display panel) were not changed in theoptical simulation.

Specifically, each of the layers in contact with the separation layerincluded in the insulating layer 705 and the insulating layer 715 was a600-nm-thick silicon oxynitride film.

To secure the flexibility of the display panel, a structure in whichstress does not concentrate on a particular film was used based on thecalculation results.

By stacking a layer having a refractive index of approximately 1.5(corresponding to a silicon oxynitride film) and a layer having arefractive index of approximately 1.9 (corresponding to a siliconnitride film) alternately so that antiphase interference occurs moreoften in the visible region, the region 110 transmitting visible lightcan have higher transmittance with respect to visible light.

FIG. 23 shows the measurement result of transmittance with respect tolight of the region 110 transmitting visible light in the display panelwhich was actually manufactured. The transmittance with respect to lightwas measured with a spectrophotometer.

As shown in FIG. 23, the transmittance with respect to light of theregion 110 transmitting visible light in the display panel which wasmanufactured has a high value, which is approximately 70% to 80% in therange of 450 nm to 650 nm, which is the peak range of an emissionspectrum of the organic EL element. Note that the measurement resultincludes the reflectivity of approximately 8% in total including thereflectivity between the substrate 701 and air and that between thesubstrate 711 and air. The absorptance of the substrate 701 and that ofthe substrate 711 are each approximately 4% to 8%. Therefore, it can beconcluded that the light transmittance of the inorganic insulating filmwhich was optically optimized was able to be increased to approximately95%.

As described above, the structure where the region transmitting visiblelight of the display panel overlaps the display region of anotherdisplay panel with the light-transmitting layer provided therebetweenwas employed, and the inorganic insulating film included in the regiontransmitting visible light was optically optimized, whereby a largedisplay device in which a seam between display panels was hardlyrecognized by a user was able to be manufactured.

Example 2

In this example, the results of manufacturing the display device of oneembodiment of the present invention are described. A display devicemanufactured in this example is a kawara-type multidisplay.

FIG. 24A is a photograph of the display device displaying an image whichwas manufactured in this example. The display device illustrated in FIG.24A includes four display panels arranged in a matrix of two rows andtwo columns. The width of the region transmitting visible light of thedisplay panel is approximately 2 mm. The display device was manufacturedin such a manner that the region transmitting visible light was providedto overlap a display region of another display panel with alight-transmitting layer provided therebetween. FIG. 4A is a schematiccross-sectional view illustrating two of the display panels included inthe display device that are attached to each other.

In the display device illustrated in FIG. 24A, a light-emitting portionhas a size of 27 inches diagonal (the size of the light-emitting portionof one display panel is 13.5 inches diagonal), 2560×1440 effectivepixels, the pixel size of 234 μm×234 μm, a resolution of 108 ppi, and anaperture ratio of 61.0%. A built-in scan driver and an external sourcedriver attached by chip on film (COF) were used.

FIG. 24B is a photograph of one display panel displaying an image. Astructure that blocks visible light such as a lead wiring or a driver isnot provided at all from an end portion of the light-emitting portion toan end portion of the display panel along two sides of the displaypanel, and the a region along two sides serve as a region transmittingvisible light. As illustrated in an enlarged view of FIG. 24B, the widthof the region transmitting visible light is approximately 2 mm. Theregion transmitting visible light has a very small thickness of lessthan 100 μm. Therefore, although the display device in this example hasa region in which at most four display panels overlap with each other, astep formed on the display surface side is extremely small; thus, a seamhardly stands out. In addition, since the display panel has flexibility,part of an FPC can be placed under the light-emitting portion of theadjacent display panel by bending the vicinity of a region to which theFPC is connected. In this way, another display panel can be provided onfour sides of the display panel, whereby a large-sized display panel iseasily realized.

The display panel illustrated in FIG. 24B is an active matrix organic ELdisplay which has a light-emitting portion with a size of 13.5 inchesdiagonal, 1280×720×RGBY effective pixels, a resolution of 108 ppi, andan aperture ratio of 61.0%.

It is preferable that the display device in this example have smallervariation in luminance among a plurality of display panels. In the casewhere a lead wiring or the like is not provided along two sides as inthe display panel in this example, the luminance of a region far from awiring is low in some cases. Thus, the display panel in this example hassix transistors and two capacitors in a pixel circuit to performinternal correction. Furthermore, the pixel arrangement where foursubpixels (RGBY) including a yellow (Y) subpixel having a high currentefficiency are arranged in a matrix of two rows and two columns wasemployed, whereby the amount of current flowing through the displaypanel is reduced and a voltage drop was suppressed.

In this example, as the light-emitting element, a tandem (stack) organicEL element emitting white light that includes a blue light-emitting unit205 and a yellow light-emitting unit 209 was used (see FIG. 25). Anintermediate layer 207 was provided between two light-emitting units.The light-emitting element was provided over a stack 201. The stack 201includes a substrate and a transistor. The light-emitting element has atop emission structure. The light from the light-emitting element isextracted outside through color filters (a yellow color filter CFY, ablue color filter CFB, a green color filter CFG, and a red color filterCFR). A reflective electrode was used as an anode 203 of thelight-emitting element, a transflective electrode was used as thecathode 211, and a microcavity structure was used. Therefore, a changein chromaticity depending on the viewing angle in the pixel arrangementof RGBY can be smaller than that in the pixel arrangement of RGBWincluding a white (W) subpixel.

FIG. 26 illustrates the measurement results of luminance when a whitecolor (luminance of 300 cd/m²) is displayed on the entire surface of thedisplay panel in this example. FIG. 26 illustrates the measurementresults of luminances at two places in the panel. One place is a regionclose to a lead wiring which corresponds to the upper left side of FIG.24B, and the other place is a region close to a region transmittingvisible light corresponding the lower right side of FIG. 24B. Theresults obtained by measuring four display panels show that there was nolarge variation between the luminances of the two places in each panel.Luminance does not decrease even in the region far from the lead wiringand close to the region transmitting visible light. The above resultsindicate that variation in luminance is less likely to be caused amongthe plurality of display panels in the display device in this example.

Note that the structure of the transistor used in this example issimilar to that in Example 1, and the detailed description is omitted.

Furthermore, in this example, 36 display panels illustrated in FIG. 24Bwere connected together, whereby an 81-inch display device illustratedin FIG. 27 was manufactured. The display device having a high resolutionof 8k4k with 7680×4320 effective pixels was manufactured.

As described in this example, in one embodiment of the presentinvention, a large-sized display device in which a seam between displaypanels is hardly recognized by a user was able to be obtained.

Example 3

In this example, the results of manufacturing the display device of oneembodiment of the present invention are described. A display devicemanufactured in this example is a kawara-type multidisplay.

First, the display panel used in the display device in this example isdescribed.

FIG. 28A is a schematic view of the display panel in this example. Thedisplay panel illustrated in FIG. 28A is an active matrix organic ELdisplay which has a light-emitting portion 250 with a size of 13.5inches diagonal, 1280×720 effective pixels, a resolution of 108 ppi, andan aperture ratio of 61.0%. The display panel includes a demultiplexer(DeMUX) 253 serving as a source driver. In addition, the display panelalso includes a scan driver 255. Two sides of the light-emitting portion250 are in contact with a region 251 transmitting visible light. A leadwiring 257 is provided along the other two sides.

A channel-etched transistor including a CAAC-OS is used as a transistor.Note that an In—Ga—Zn-based oxide is used for the oxide semiconductor.

As the light-emitting element, a tandem (stack) organic EL elementemitting white light is used. The light-emitting element has a topemission structure, and the light from the light-emitting element isextracted outside through a color filter.

FIG. 28B is a schematic view of overlapping four display panels in amatrix of two rows and two columns. FIG. 28C shows a cross-sectionalschematic view taken along a dashed dotted line X-Y in FIG. 28B.

The display device in this example is formed by overlapping a pluralityof display panels so that a non-display region between display regionsis made small. Specifically, the light-transmitting layer 103 isprovided between the region 251 transmitting visible light of an upperdisplay panel and the light-emitting portion 250 of a lower displaypanel.

A structure that blocks visible light such as a lead wiring or a driveris not provided at all from an end portion of the light-emitting portion250 to an end portion of the display panel along two sides of thedisplay panel, and the a region along two sides serve as a region 251transmitting visible light. The width of the region 251 transmittingvisible light of the display panel is 2 mm. The thickness of the region251 transmitting visible light (also referred to as a thickness of onedisplay panel) is very small, which is less than 100 μm. Therefore,although the display device in this example has a region in which atmost four display panels overlap with each other, a step formed on thedisplay surface side is extremely small; thus, a seam hardly stands out.

The four display panels have flexibility. Thus, as illustrate in FIG.28C, a region near the FPC 112 a of the lower display panel can be bentso that part of the lower display panel and part of the FPC 112 a can beplaced under the light-emitting portion 250 of the upper display paneladjacent to the FPC 112 a. As a result, the FPC 112 a can be placedwithout physical interference with the rear surface of the upper displaypanel. In this way, another display panel can be provided on four sidesof the display panel, whereby a large-sized display panel is easilyrealized.

In this example, an absorption film including attachment layers on bothsurfaces of a base material was used as the light-transmitting layer103. With use of the attachment film, two display panels included in thedisplay device can be detachably attached to each other. An attachmentlayer on one surface of the light-transmitting layer 103 can be attachedto the substrate 152 a, and an attachment layer on the other surface ofthe light-transmitting layer 103 can be attached to the substrate 151 b.

In FIG. 28B, the light-transmitting layer 103 includes not only aportion overlapping with the region 251 transmitting visible light, butalso a portion overlapping with the light-emitting portion 250. In FIG.28C, the light-transmitting layer 103 overlaps with the entire region251 transmitting visible light from an end portion of the substrate 151b, and also overlaps with part of the region 155 b containing a displayelement. Note that the light-transmitting layer 103 is not provided on acurved region of the display panel that is close to a region to which anFPC is connected illustrated in FIG. 28C. However, thelight-transmitting layer 103 may be provided on a curved region of thedisplay panel depending on the thickness or flexibility of thelight-transmitting layer 103.

Each of the display panels was formed by attaching a substrate and anelement layer with a bonding layer. For example, as illustrated in FIG.28C, the substrate 151 a, the substrate 152 a, the substrate 151 b, andthe substrate 152 b are attached to the element layer 153 a, the elementlayer 153 a, the element layer 153 b, and the element layer 153 brespectively, with the bonding layer 157. Each of the element layersincludes a region 155 containing a display element and a region 156including a wiring electrically connected to the display element.

In addition, the manufactured display panel was subjected to a bendingtest. FIGS. 29A to 29C show how the bending test was performed. A bentportion is a portion shown by a dotted line in FIG. 28A, which is aregion between the light-emitting portion 250 and the FPC connectedportion and includes lead wirings used for a power source. Changing thedisplay panel in shape from the state in FIG. 29A to the state in FIG.29B and returning to the state in FIG. 29A was counted as one bending,and the bending was repeated 100,000 times. The curvature radius forbending the display panel was 5 mm. In the bending test, one bending wasperformed in approximately 2 seconds. FIG. 29C is a photograph of thedisplay panel seen from a direction denoted by an arrow in FIG. 29B.

FIG. 29D is a photograph of an image displayed on the display panelbefore the test. FIG. 29E is a photograph of an image displayed on thedisplay panel after the test. A display defect was not observed in thedisplay panel after the test.

Note that the luminance of the light-emitting portion 250 might beperceived different between in part which is viewed through the region251 transmitting visible light and part which is viewed without throughthe region 251 transmitting visible light. Therefore, as illustrated inFIG. 30A, it is preferable that an image be displayed with a higherluminance in part overlapping with the region 251 transmitting visiblelight as compared with the other parts (for example, a data voltage ofthe part overlapping with the region 251 transmitting visible light isset higher than the other parts) because luminance of the entirelight-emitting portion 250 can be uniform.

In this example, 36 display panels illustrated in FIG. 28A were arrangedin a matrix of six rows and six columns, whereby an 81-inch displaydevice illustrated in FIG. 31 was manufactured.

In this example, the display panels were driven by respective drivercircuits. As illustrated in FIG. 30B, a signal output from an 8 krecorder was divided into 36 parts and input to respective drivercircuits. The timing of scanning in the first stage of each displaypanel was set to be at the same time.

In this example, a display device illustrated in FIG. 31 having a highresolution of 8k4k with 7680×4320 effective pixels was manufactured.Note that the weight of one display panel including an FPC isapproximately 26 g, and the weight of 36 display panels is less than orequal to 1 kg (here, the weight of the display panel and an FPC ismentioned, and the weight of a frame for fixing the display panel, andthe like is not included).

FIG. 32 shows an observation result of a seam between the displaypanels. Note that an image displayed in FIG. 31 is different from thatin FIG. 32. FIG. 32 shows a portion where the display panels overlapwith each other (the width of 2 mm). As described above, with the use ofone embodiment of the present invention, a seam between the displaypanels is hardly recognized or is negligible in a distance between thedisplay panel and a user even if it can be observed in a near distance.

As described above, in one embodiment of the present invention, alarge-sized display device in which a seam between display panels ishardly recognized by a user was able to be obtained.

EXPLANATION OF REFERENCE

10: display device, 11: display region, 15: column, 16: wall, 100:display panel, 100 a: display panel, 100 b: display panel, 100 c:display panel, 100 d: display panel, 101: display region, 101 a: displayregion, 101 b: display region, 101 c: display region, 101 d: displayregion, 102: region, 102 a: region, 102 b: region, 103:light-transmitting layer, 103 a: light-transmitting layer, 103 a 1:light-transmitting layer, 103 a 2: light-transmitting layer, 103 b:light-transmitting layer, 103 b 1: light-transmitting layer, 103 b 2:light-transmitting layer, 110: region transmitting visible light, 110 a:region transmitting visible light, 110 b: region transmitting visiblelight, 110 c: region transmitting visible light, 110 d: regiontransmitting visible light, 112 a: FPC, 112 b: FPC, 120: region blockingvisible light, 120 a: region blocking visible light, 120 b: regionblocking visible light, 120 c: region blocking visible light, 123: FPC,131: resin layer, 132: protective substrate, 133: resin layer, 134:protective substrate, 141: pixel, 141 a: pixel, 141 b: pixel, 142 a:wiring, 142 b: wiring, 143 a: circuit, 143 b: circuit, 145: wiring, 151:substrate, 151 a: substrate, 151 b: substrate, 152: substrate, 152 a:substrate, 152 b: substrate, 153 a: element layer, 153 b: element layer,154: bonding layer, 155: region, 155 a: region, 155 b: region, 156:region, 156 a: region, 156 b: region, 157: bonding layer, 201: stack,203: anode, 205: blue light-emitting unit, 207: intermediate layer, 209:yellow light-emitting unit, 211: cathode, 250: light-emitting portion,251: region transmitting visible light, 253: demultiplexer, 255: scandriver, 257: lead wiring, 301: display portion, 302: pixel, 302B:sub-pixel, 302G: sub-pixel, 302R: sub-pixel, 302 t: transistor, 303 c:capacitor, 303 g(1): scan line driver circuit, 303 g(2): imaging pixeldriver circuit, 303 s(1): image signal line driver circuit, 303 s(2):imaging signal line driver circuit, 303 t: transistor, 304: gate, 308:imaging pixel, 308 p: photoelectric conversion element, 308 t:transistor, 309: FPC, 311: wiring, 319: terminal, 321: insulating layer,328: partition, 329: spacer, 350R: light-emitting element, 351R: lowerelectrode, 352: upper electrode, 353: EL layer, 353 a: EL layer, 353 b:EL layer, 354: intermediate layer, 360: bonding layer, 367B: coloringlayer, 367BM: light-blocking layer, 367G: coloring layer, 367 p:anti-reflective layer, 367R: coloring layer, 380B: light-emittingmodule, 380G: light-emitting module, 380R: light-emitting module, 390:touch panel, 500: display portion, 500TP: touch panel, 501: displayportion, 503 g: driver circuit, 503 s: driver circuit, 505: touch panel,505B: touch panel, 509: FPC, 590: substrate, 591: electrode, 592:electrode, 593: insulating layer, 594: wiring, 595: touch sensor, 597:bonding layer, 598: wiring, 599: connection layer, 600: input portion,602: sensor unit, 603 d: driver circuit, 603 g: driver circuit, 650:capacitor, 651: electrode, 652: electrode, 653: insulating layer, 667:window portions, 670: protective layer, 701: substrate, 703: bondinglayer, 705: insulating layer, 711: substrate, 713: bonding layer, 715:insulating layer, 804: light-emitting portion, 806: driver circuitportion, 808: FPC, 813: gate insulating layer, 814: conductive layer,815: insulating layer, 817: insulating layer, 817 a: insulating layer,817 b: insulating layer, 820: transistor, 821: insulating layer, 822:bonding layer, 823: spacer, 824: transistor, 825: connector, 830:light-emitting element, 831: lower electrode, 832: optical adjustmentlayer, 833: EL layer, 835: upper electrode, 845: coloring layer, 847:light-blocking layer, 849: overcoat, 856: conductive layer, 857:conductive layer, 857 a: conductive layer, 857 b: conductive layer,7000: display portion, 7001: display portion, 7100: mobile phone, 7101:housing, 7103: operation button, 7104: external connection port, 7105:speaker, 7106: microphone, 7200: television set, 7201: housing, 7203:stand, 7211: remote controller, 7300: portable information terminal,7301: housing, 7302: operation button, 7303: information, 7400: lightingdevice, 7401: stage, 7402: light-emitting portion, 7403: operationswitch, 7500: portable information terminal, 7501: housing, 7502:member, 7503: operation button, 7600: portable information terminal,7601: housing, 7602: hinges, 7650: portable information terminal, 7651:non-display portion, 7700: portable information terminal, 7701: housing,7703 a: button, 7703 b: button, 7704 a: speaker, 7704 b: speaker, 7705:external connection port, 7706: microphone, 7709: battery, 7800:portable information terminal, 7801: band, 7802: input-output terminal,7803: operation button, 7804: icon, and 7805: battery

This application is based on Japanese Patent Application serial no.2014-156168 filed with Japan Patent Office on Jul. 31, 2014, JapanesePatent Application serial no. 2014-219131 filed with Japan Patent Officeon Oct. 28, 2014, Japanese Patent Application serial no. 2014-243195filed with Japan Patent Office on Dec. 1, 2014, and Japanese PatentApplication serial no. 2015-109642 filed with Japan Patent Office on May29, 2015, the entire contents of which are hereby incorporated byreference.

1. A display device comprising: a first display panel being at leastpartly flexible; and a second display panel being at least partlyflexible, wherein the first display panel includes a first region and asecond region, wherein the first region has a function of performingdisplay, wherein the second region has a function of blocking visiblelight, wherein the second display panel includes a third region and afourth region, wherein the third region has a function of performingdisplay, wherein the fourth region has a function of transmittingvisible light, wherein the third region is adjacent to the fourthregion, wherein the second display panel is bent in the third region orin the fourth region, wherein the fourth region overlaps the firstregion, wherein a first flexible printed circuit is in contact with andelectrically connected to the first display panel, and wherein a secondflexible printed circuit is in contact with and electrically connectedto the second display panel.
 2. The display device according to claim 1,wherein the first region includes a light-emitting element, wherein thethird region includes a light-emitting element, and wherein the fourthregion includes a bonding layer.
 3. The display device according toclaim 1, wherein the second display panel includes a fifth region,wherein the fifth region is adjacent to the third region, wherein thefifth region has a function of blocking visible light, and wherein thefifth region does not include a region overlapping with the firstregion.
 4. The display device according to claim 3, wherein the fifthregion functions as a wiring portion electrically connected to alight-emitting element included in the third region.
 5. The displaydevice according to claim 1, further comprising a light-transmittinglayer, wherein the light-transmitting layer includes alight-transmitting material having a transmittance with respect to lightin a wavelength range of 450 nm to 700 nm of 90% or more.
 6. The displaydevice according to claim 5, wherein the light-transmitting material hasa refractive index of higher than or equal to 1.3 and lower than orequal to 1.8.
 7. The display device according to claim 5, wherein thelight-transmitting layer is detachably in contact with at least one ofthe first display panel and the second display panel.
 8. The displaydevice according to claim 5, wherein the light-transmitting layerincludes an inert material.
 9. The display device according to claim 5,wherein the light-transmitting layer includes a nonvolatile material.10. The display device according to claim 5, wherein thelight-transmitting layer has a material with a viscosity of greater thanor equal to 1 mPa·s and less than or equal to 1000 Pa·s.
 11. Anelectronic device comprising: the display device according to claim 1,and an antenna, a battery, a housing, a speaker, a microphone, anoperation switch, or an operation button.
 12. A display devicecomprising: a first display panel being at least partly flexible; and asecond display panel being at least partly flexible, wherein the firstdisplay panel includes a light-blocking region, wherein a part of thesecond display panel overlaps a part of the first display panel, whereinthe second display panel is bent in a region having a function ofperforming display or a region overlapping with the first display panel,wherein a first flexible printed circuit is in contact with andelectrically connected to the first display panel, and wherein a secondflexible printed circuit is in contact with and electrically connectedto the second display panel.
 13. The display device according to claim12, further comprising a light-transmitting layer, wherein thelight-transmitting layer includes a light-transmitting material having atransmittance with respect to light in a wavelength range of 450 nm to700 nm of 90% or more.
 14. The display device according to claim 13,wherein the light-transmitting material has a refractive index of higherthan or equal to 1.3 and lower than or equal to 1.8.
 15. The displaydevice according to claim 13, wherein the light-transmitting layer isdetachably in contact with at least one of the first display panel andthe second display panel.
 16. The display device according to claim 13,wherein the light-transmitting layer includes an inert material.
 17. Thedisplay device according to claim 13, wherein the light-transmittinglayer includes a nonvolatile material.
 18. The display device accordingto claim 13, wherein the light-transmitting layer has a material with aviscosity of greater than or equal to 1 mPa·s and less than or equal to1000 Pa·s.
 19. An electronic device comprising: the display deviceaccording to claim 12, and an antenna, a battery, a housing, a speaker,a microphone, an operation switch, or an operation button.